DEPARTMENT OF EPIDEMIOLOGY AND PUBLIC HEALTH
Title: Ocular cancer incidence in Ireland – histological subtypes,
staging and treatment outcomes between 1992 and 2012
By
Muthukumaran Chitambaram
Student Number: 114223584
Head of Department: Prof. Ivan Perry
Project Supervisor: Dr. Zubair Kabir
Project Tutor: Ms. Shelly Chakraborty PhD Student
Report on research completed and submitted in fulfilment of the
examination for the Masters of Public Health at University College
Cork, September 2015.
[1]
Declaration form
University College Cork
Department of Epidemiology and Public Health
Title of Thesis:
Ocular cancer incidence in Ireland – histological subtypes,
staging and treatment outcomes between 1994 and 2012
Name of Student: Muthukumaran Chitambaram
Student Number: 114223584
I declare that the content of this assignment is all my own work.
Where the work of others has been used to augment my
assignment it has been referenced accordingly.
Signed: CT. Muthukumaran
Date: 02/10/2015
Word count: Approximately 13,752 words
[2]
Acknowledgements
For the ancestors who paved the path before me upon whose shoulders I stand. A special
thanks to my father Mr. Chitambaram Periyaiya, mother Ms. Rajeswari Chitambaram, wife
Ms. Prema Muthukumaran and daughters Charulata and New born who have always
supported and prayed for me throughout my education and life.
My deep gratitude goes first to my supervisor Dr. Zubair Kabir, who expertly guided me
throughout my MPH dissertation by understanding me and bringing the best out of me. I am
extremely grateful for the assistance and support throughout the course he provided. I am
using this opportunity to thank all the professors and lecturers who taught me in my postgraduation. I would like to express my sincere gratitude to the Department of Epidemiology
and Public Health, University College Cork for letting me fulfil my dream of being a student
here.
I take this opportunity to thank my friends Ms. Laura McCarthy and Mr. Mahesh Dayalan
and my tutor Ms. Shelly Chakraborty for the timely advice and support they provided. I am
thankful for the aspiring guidance provided by Dr. Mahalakshmi Prasad in many difficult
situations.
A special thanks to Dr. Sanjiv Aggarwal cardiologist for always supporting me in all my
works from the beginning of my career. I would also like to thank my previous institutions I
worked and studied in particular Cancer Institute (WIA), Adyar. A special thanks to my
radiation oncology professors Dr. A. Vasanthan and Dr. G. Selvaluxmy for the knowledge
they have provided.
Thank you
Muthukumaran
[3]
Table of content
Chapter
Page
A. List of Tables and Figures………………………………………………………………......7
B. List of Abbreviations………………………………………………………………………10
C. Glossary......................................................................................................................….....12
D. Abstract……………………………………………………………………………………13
1. Aim, objectives and rationale………………………………………………………………14
1.1. Rationale and importance to public health……………………………………………….14
1.2. General aims……………………………………………………………………………..16
1.3. Objectives………………………………………………………………………………..17
2. Literature Review………………………………………………………………………….18
2.1. Introduction……………………………………………………………………………...18
2.1.1. Ocular neoplasm according to morphological types…………………………………..19
2.1.2. Histology………………………………………………………………………………21
2.2. Objectives of the literature review………………………………………………………21
2.3. Search strategy and study selection criteria……………………………………………..22
2.4. Methods of searching the literature………………………………………………………23
2.4.1. Electronic database searching………………………………………………………….23
2.4.2. Book searching………………………………………...………………………………23
2.4.3. Reference list searching………………………………………………………………..24
[4]
2.5. Literature data extraction and quality appraisal methods………………………………...25
2.5.2. Summary and conclusion of the literature review……………………………………...29
3. Data and Methodology……………………………………………………………………..32
3.1. NCRI background information…………………………………………………………..32
3.2. Administrative structure…………………………………………………………………34
3.3. Data collection and management………………………………………………………...35
3.4. Ethical aspects……………………………………………………………………………37
3.5. Data used for analysis……………………………………………………………………37
3.6. Data cleaning…………………………………………………………………………….38
3.7. Descriptive statistics……………………………………………………………………..39
3.8. Analysis plan for the specific objectives…………………………………………………39
3.8.1. Objective 1……………………………………………………………………………..39
3.8.2. Objective 2……………………………………………………………………………..41
3.8.3. Objective 3……………………………………………………………………………..41
4. Results……………………………………………………………………………………..42
4.1. Descriptive statistics……………………………………………………………………. 42
4.2. Results for the specific objectives……………………………………………………….47
4.2.1. Age-Standardized incidence rates……………………………………………………..47
4.2.2. Kaplan-Meier survival curve with cos proportional hazard analysis……….…………51
5. Discussion and conclusion…………………………………………………………………64
[5]
5.1. Retinoblastoma incidence…………………………………………………..……………65
5.2. Ocular Melanoma Incidence……………………………………………….….…………65
5.3. Ocular melanoma and Gender…………………………………………….….…………..66
5.4. Screening and ocular cancer…………………………………………………….…….….66
5.5. Ocular cancer survival rate by morphology………………………………………………67
5.6. Ocular cancer survival rates by age-group……………………………………………….67
5.7. Strengths and limitations of the study……………………………………………….…...68
5.8. Implication for public health policy and recommendations for the future……….………68
5.9. Conclusions……………………………………………………………………………...69
6. References…………………………………………………………………………………70
7. Appendices………………………………………………………………………………...76
[6]
A. List of Tables and Figures
Table
Title
Page
Number
1
Inclusion & exclusion criteria.
2
Search terms used in advanced search of database
3
Quality assessment summary
4
Data used and description
5
Distribution of new Ocular Cancer cases in the Republic of
Ireland (1994-2012) by socio-demographic characteristics
across five grouped time-periods
6
Distribution of new specific morphologic types of ocular
cancer cases in the Republic of Ireland (1994-2012) by sociodemographic characteristics
7
Distribution of new specific morphologic types of ocular
cancer cases in the Republic of Ireland (1994-2012) by clinical
characteristics
8
Age-Standardized Incidence Rates (per 100,000) of Total
Ocular Cancer cases in the Republic of Ireland (1994-2012)
by age-groups across five grouped time-periods
9
Age-Standardized Incidence Rates (per 100,000) of Total
Ocular Cancer cases in the Republic of Ireland (1994-2012)
by gender across five grouped time-periods
10
Age-Standardized Incidence Rates (per 100,000) of Total
Ocular Cancer cases in the Republic of Ireland (1994-2012)
[7]
by specific morphologic types across five grouped timeperiods
11
Age-Standardized
Incidence
Rates
(per
100,000)
of
Melanoma cases in the Republic of Ireland (1994-2012) by
age-groups across five grouped time-periods
12
Age-Standardized
Incidence
Rates
(per
100,000)
of
Melanoma cases in the Republic of Ireland (1994-2012) by
gender across five grouped time-periods
13
Age-Standardized
Incidence
Rates
(per
100,000)
of
Retinoblastoma cases in the Republic of Ireland (1994-2012)
by age-groups across five grouped time-periods
14
Age-Standardized
Incidence
Rates
(per
100,000)
of
Retinoblastoma cases in the Republic of Ireland (1994-2012)
by gender across five grouped time-periods
15
Univariate and Multivariable Cox Proportional Hazards
Regression analysis with covariates
[8]
Figure
Title
Page
Number
1
Flow chart diagram for search strategy
2
The governance structure of the National Cancer Registry
Ireland
3
Source: National Cancer Registry Ireland
4
Kaplan-Meier of 1994-2012 Ocular Cancer cases by gender
5
Kaplan-Meier of 1994-2012 Ocular Cancer cases by agegroup
6
Kaplan-Meier of 1994-2012 Ocular Cancer cases by
morphologic types
7
Kaplan-Meier of 1994-2012 Ocular Cancer cases by smoking
status
8
Kaplan-Meier of 1994-2012 Ocular Cancer cases by
anatomic sites (ICDs)
9
Kaplan-Meier of 1994-2012 Ocular Cancer cases by timeperiods
10
Kaplan-Meier of 1994-2012 Ocular Cancer cases by gender
and age-groups
11
Kaplan-Meier of 1994-2012 Ocular Cancer cases by residual
12
Kaplan-Meier of 1994-2012 specific morphologic ocular
cancer cases by age-groups
13
Kaplan-Meier of 1994-2012 specific morphologic ocular
cancer cases by gender
[9]
B. List of Abbreviations
NCRI- National Cancer Registry Ireland
ASR- Age-standardised rates
HSE- Health services executives
SCC- Squamous cell carcinoma
CASP-Critical Appraisal Skills Programme
US- United States
UK- United Kingdom
TROs-Tumour registration officers
HR- Hazards ratios
CI- Confidence intervals
KM- Kaplan-Meier
WHO- World Health Organisation
UV- Ultra violate radiation
DNA- Deoxyribonucleic acid
ERMS- Embryonal rhabdomyosarcoma
COMS- Collaborative ocular melanoma study
HIV- Human immunodeficiency virus
HPV- Human papilloma virus
OSSN- Ocular surface squamous neoplasia
[10]
GP- General Practitioner
[11]
C. Glossary
Confidence interval- indicates that there is a 95% probability that the effect of treatment in the
whole population lies within the stated range (Peat, Barton and Elliott, 2008).
Confounders- Patient characteristics that may affect the results a study is trying to measure.
Hazards ratio- The risk of the event in a study group divided by the risk of the event in a
reference group.
Incidence- the number of new cases of disease within a given time period.
Log rank test- Statistic used to compare the evens observed and expected between two studies.
p-Value- Probability that a difference between study groups would have occurred if null
hypothesis was true.
Variable- any characteristic or attributable that can be measured.
Melanoma- A type of cancer that develops from the melanocytes (MedicineNet, 2015).
Squamous cell cancer- A type of cancer of epithelial cell origin.
Retinoblastoma- A cancer that rapidly develops from immature cells of retina.
Age-Standardized rate- A technique used to allow populations to be compared when the age
profile of the populations are quite different.
[12]
D. Abstract
Background: Ocular cancer is a significant public health problem worldwide as it affects the
vision and psychology of the patients and their family. In Ireland from 1994 to 2012 a total of
861 ocular cases has been diagnosed and treated, out of which 327 died and 534 living with
significant morbidity.
Methods: Population-based data, diagnosed with ocular cancer (ICD 10 codes C690- C699),
(N=861), was obtained from the National Cancer registry Ireland. We analysed morphology
wise incidence trend of ocular neoplasm from the year 1994-2012, and calculated the Age
standardized rates for the years. Survival rates were also examined using Kaplan-Meier curve
and cox proportional hazard with different covariates for the years 1994-2012.
Results: Increased (163%) age specific retinoblastoma incidence is noted during the study
period 1994-2012. In Ireland 78% of all ocular cancer is melanoma in morphology and older
age group is four to five times more prone to get melanoma. There is a relative increase of 29%
in male melanoma incidence during the years 1994-2012. Survival rates decrease in older age
groups in 30-60 age-group a four time (HR=3.76; CI=1.81-7.79: p=0.00) and for above 60 agegroup a nine times (Hr=9.32: CI= 4.60-18.89; p=0.00) is noted.
Conclusion: Further research is needed in the field of retinoblastoma and Male ocular
melanoma as there is a significant increase in incidence rates. Screening in under five age for
retinoblastoma should also be studied for its effect on preventing loss of vision and eye ball.
Awareness should be created on artificial tanning and UV in ocular melanoma prevention.
[13]
Chapter 1
1 Aims, objectives and rationale
1.1 Rationale and importance to public health
Ocular neoplasm refers to a cancerous growth in any part of the eye. Eye cancers can be divided
into primary and secondary (TheFreeDictionary.com, 2015). Cancer affecting the inside of the
eye are intraocular and those affecting the outside of the eye are extraocular (cancer, 2015). In
Ireland 19,200 cancer cases registered annually according to 2009 to 2011 data. The incidence
rate of invasive cancers is 425 case per 100,000 population per year. Every year there is 0.5%
increase in incidence as per 2008-2010 data. Ocular cancers are listed in other invasive cancers
which accounts for 37.3 per 100,000 population (Ncri.ie, 2015). In Ireland cancer of eye
accounts between 26 and 69 cases a year from 1994 to 2012(Ncri.ie, 2015).
Eye cancer morphology, prevalence, treatment and outcome differs for each and every country.
Melanoma dominates in most of the countries followed by lymphoma and squamous cell
carcinoma. In Ireland National Cancer Registry of Ireland (NCRI) has materials regarding
melanoma which is categorised in skin melanoma (Ncri.ie, 2015). Other than that there is very
less known about the other types and outcome in Ireland.
Ultraviolet (UV) radiation is a major risk factor for most skin cancers. Sunlight, tanning lamps
and tanning beds are also sources of UV rays (Cancer.org, 2015). Exposure to UV rays is a risk
factor for skin cancer. UV rays damage the DNA of skin cells. Skin cancers start when this
damage affects the DNA of genes that control skin cell growth. UVA and UVB rays can
damage the DNA and cause skin cancer. Melanoma of the eye has also been linked to sun
exposure in some studies (Cancer.org, 2015). Skin cancer incidence is strongly associated with
the regional distribution and with the UVB radiation (Chang et al., 2010). The UV index is a
measure of the level of UV radiation reaching the earth’s surface. Summer in Ireland 2014 UV
[14]
index was measured. A total of 181 days from April to September was measured for UV rays.
It is found that the south and west of the Ireland had higher UV ray level. UV level index >=3
in Cork is 172 days, in Dublin 147 days, in Galway 163 days in Limerick 162 days and in
Donegal 150 days. Cork had 95% days with high UV index during the 2014 summer (Cancer.ie,
2015). Melanoma is largely a sporadic event, risk factors include iris colour, ability to tan,
northern European ancestry, and rarely family history. Melanosis is also associated with
melanoma. Early diagnosis I s associated with best prognosis (Eyewiki.aao.org, 2015).
Childhood ocular cancer which are strictly confined to young age group. Retinoblastoma and
embryonal rhabdomyosarcoma have genetic aetiology and occurs in young age group.
Retinoblastoma is the most common intraocular malignancy affecting children. The incidence
varies from 3.4 to 42.6 cases per million live births by country. RB1 gene is a tumour
suppressing gene which is affected in this disease. Red Reflex Examination in neonates, infants
and children is recommended for early diagnosis as a screening. Early diagnosis can maximize
the patient’s visual prognosis and survival. Present illness, family history and ophthalmic
examination are critical for diagnosis (Eyewiki.aao.org, 2015). Awareness, screening and early
diagnosis helps to save the eye.
Rhabdomyosarcoma is the most common childhood sarcoma of soft tissue. Common age of
occurrence is 7 to 8 years of age. RMS develops in the orbital soft tissues. The disease may be
spontaneous or associated with familial syndromes, p53 tumour suppressor gene, or congenital
malformation. Ophthalmoscopy examination and family history helps the diagnosis
(Eyewiki.aao.org, 2015).
The American Academy of Paediatrics policy statement on Red Reflex Examinations in
Neonates, Infants, and Children recommends that all neonates, infants, and children should
have an examination of the red reflex before discharge from the neonatal nursery and at all
[15]
subsequent routine health supervision visits. Early diagnosis of retinoblastoma can maximize
the patient’s visual prognosis as well as survival rate (Eyewiki.aao.org, 2015).
This study of ocular cancer incidence, risk factors, and morphology is an initial step for
planning a screening program and creating an awareness among public and professionals. This
study is an initial process to give a general knowledge about the incidence, risk demography,
outcome associated with different morphology, survival time, recurrence. The result of this
research will provide local evidence in terms of pattern of ocular cancer, morphology, and risk
group which can provide an additional insight into existing ocular cancer diagnosis, and
treatment methods in health services in Ireland.
This thesis is structured as follows: this section details a brief background to the thesis and
outlines the aims and objectives. Following on from this, section two provides a critical review
of all relevant literature relating to ocular cancer incidence and survival. Information on the
data collection procedures adopted by the NCRI team are described in section three. This
section also provides a detailed description of the methodology employed in the secondary
analysis of the dataset. Section four then provides a detailed analysis of the results of the
statistical tests applied, while section five concludes with a discussion of the findings,
examining their implications and limitations, and the potential for future research.
1.2 General aim
A cross sectional study to study the incidence from (1994-2012) and survival rate of ocular
cancer in Ireland using National Cancer Registry Population level data. Stratified analysis will
be used to access the values for variables age-group, gender and morphology.
Secondary aim of the study is to do a cross-sectional comparison of ocular cancer morphology
using individual-level data received from National Cancer Registry Ireland.
[16]
1.3 Objectives
To analyse yearly incidence, Age-Standardised incidence of ocular cancer in republic
of Ireland between 1994 and 2012.
To stratify estimated age standardised incidence by gender, Age group, and
Morphology.
To determine the age, gender and morphological wise survival rates in ocular cancer
from 1994 to 2012.
To examine the association of life-style risk factors (sex, age-group, smoking,
morphology, tumour site and year of incidence) with ocular neoplasm (1994 -2012).
[17]
Chapter 2
2. Literature Review
2.1. Introduction
Ocular neoplasm or eye cancer refers to a cancerous growth in any part of the eye. Some eye
cancers are primary, while other represent metastases from primary cancers elsewhere in the
body (TheFreeDictionary.com, 2015). Eye cancer is one of the rarest cancers. Melanoma of
the eye is the most common type of eye cancer among adults and retinoblastoma in children.
In United Kingdom eye cancer amounts to 430 every year (Nhs.uk, 2015). In United States
every year 2,580 new eye cancer cases are diagnosed and contributes to 270 deaths due to the
disease (Cancer.org, 2015). In Ireland 69 new cases diagnosed during the year 2012(Ncri.ie,
2015). Melanoma accounts for 70% of all ocular cancer according to the studies in United
States (Cancer.org, 2015).
In Ireland 50 eye cancer case where registered during the year 2009 and the total number of
cancer cases that year is 19,200. According to this eye cancer accounts for only 0.26 % of all
cancer cases (Ncri.ie, 2015). In Ireland 90% of primary invasive melanoma cases arises in skin
and 5% in the eye (Anon, 2015). According to the NCRI cancer trend January 2011 melanoma
skin shows an increasing trend in all age group. Age and incidence is positively associated in
skin melanoma. In Europe Scandinavian countries have higher risk than other European
countries and Ireland is the 4th highest in the list during 2008. According to 2008 study there is
a 5.8% for males and 308% for females increase annually in melanoma incidence in Ireland.
Age standardised incidence rate are also increasing by 4.5% in men and 2.0% in female
annually in Ireland. Ocular melanoma metastatic disease was diagnosed at a 25% and 34%
rate at 5 years and 10 years respectively in the collaborative ocular melanoma study (COMS)
with liver affected in 89% of the time(Eyewiki.aao.org, 2015). The mortality rate diagnosis of
[18]
metastatic disease was 80% at first year and 92% at second year (Development of Metastatic
Disease After Enrollment in the COMS Trials for Treatment of Choroidal Melanoma, 2005).
Human eye consists of sclera a white part, cornea a clear bulging surface in front of the eye,
Iris a heavily pigmented muscle, two chambers one anterior and one posterior to iris, Ciliary
body holds the lens and controls the movement, choroid lies between the retina and sclera,
Vitreous humoral which fills space between lens and retina, retina is located in the back of the
eye ball and the eye lid which is anterior to all and protects the eye (Nei.nih.gov, 2015).
Cancer of the eyes is broadly divided into two category as intraocular and extraocular. The
most common intraocular tumour is melanoma followed by lymphoma in adult and
retinoblastoma in children. Intraocular melanoma has two different kinds of cells which is
spindle cell and epithelioid cells. Lymphoma is of two kinds one is Hodgkin and other is nonHodgkin (Cancer.org, 2015). Extra ocular or tumour around the eye ball may affect
conjunctiva, cornea, eyelid, adnexa, muscle, nerves and skin around the eyeball. Melanoma
skin, basal cell carcinoma, rhabdomyosarcoma and squamous cell cancer are the few which
affects the extra ocular parts (Cancer.org, 2015), (Cancer.Net, 2012)
2.1.1. Ocular neoplasm according to morphological type
Adenocarcinoma is a cancerous tumour of epithelial cell origin that has glandular origin and
characteristics. Risk factor for adenocarcinoma differs for each and every site. Strong sunlight,
smoking, male sex, older age group, and genetic are some of the risk factors for
adenocarcinoma (Cancer.org, 2015). Adenocarcinoma of small intestine has a 55% five years
survival for stage I and 5% five year survival for stage IV disease (Cancer.org, 2015).
Embryonal rhabdomyosarcoma (ERMS) is derived from mesenchymal precursors of
mesodermal origin. ERMS accounts for 70 – 80% of all RMS tumours, and usually occurs in
[19]
young children (Atlasgeneticsoncology.org, 2015). Cells of this tumour have lost a small piece
of chromosome 11 that came from mother, and it has been replaced by a second copy of that
part of the chromosome from the father. This seems to make the IGF2 gene on chromosome
11 overactive (Cancer.org, 2015). Orbital rhabdomyosarcoma is the most common childhood
soft tissue sarcoma accounting for approximately 5% of all childhood cancers in United States.
Survival has increased due to the treatment modalities which is mostly combined. Embryonal
cell type of rhabdomyosarcoma has a 94% five year survival rate (Eyewiki.aao.org, 2015).
Retinoblastoma is a rare form of cancer that rapidly develops from the immature cells of retina.
It is the most common malignant tumour of the eye in children. Retina is the specialized lightsensitive tissue at the back of the eye that detects light and colour. The most common first sign
of retinoblastoma is a visible whiteness in the pupil called “cat’s eye reflex” or leukocoria.
Mutation in the RB1 gene are responsible for most cases of retinoblastoma. A small percentage
of retinoblastoma are caused by deletion in the region of chromosome 13 that contains the RB1
gene. In addition RB1 affected children usually also have intellectual disability, slow growth,
and distinctive facial features such as prominent eyebrows, short nose with a broad nasal
bridge, and ear abnormalities. People with germinal retinoblastoma may have a family history
of the disease, and they are at risk of passing on the gene to next generation (Genetics Home
Reference, 2015). Treatment options depend on the size of the tumour. Small tumours may be
treated by laser surgery or cryotherapy. Large tumours and local tumours are treated with
radiotherapy. Chemotherapy may be needed if the tumour has spread beyond the eye. The eye
may need removal (enucleation) if the tumour does not respond to other treatments (Updated
by: Adam S. Levy, 2015).
Melanoma affects all parts of the eye uvea, ocular, choroid, ciliary body, iris, eyelid, and
conjunctiva. Melanoma is more common in skin and has the same risk factor. UV rays
exposure, ability to tan, and colour of the iris are some risk factors for melanoma (Holly, Aston
[20]
and Char, 1990). Treatment for melanoma differs according to the size, greater the size more
chance of enucleation. Most of the patients are treated with combined radiotherapy and
chemotherapy. Metastasis occurs at 5, 10, and 20 years in 6%, 12% and 20%. Outcome of the
disease is not treatment specific and is mostly associated with virulence, site and age of the
patient. Radiotherapy is a preferred method of treatment so as to save the globe.
2.1.2 Histology
Most common ocular cancer in adult is Melanoma. Incidence of melanoma varies from 55%75% of all eye cancers. Retinoblastoma is the most common childhood tumour in eye.
Incidence is estimated to be 1 in 18,000 to 30,000 live birth (Atlasgeneticsoncology.org, 2015).
Squamous cell carcinoma of the eye amounts for 1-2.8 per 100,000 population in United States
(Wikipedia, 2015). Adenocarcinoma, embryonal rhabdomyosarcoma, mixed epithelioid and
spindle cell carcinoma, sarcoma are other some cancer which affects eye (Wikipedia, 2015).
2.2. Objective of the literature review
The purpose of the study is to examine time trend and morphology wise incidence, and survival
of ocular cancer. The main objective of this literature reviews was to systematically collect and
critically summarise information available from relevant papers related to ocular cancer trends
globally.
The literature review focused also on risk factors which can be avoided and of public health
importance.
The literature review primarily assessed population based evidence which analysed trend and
morphology related to ocular cancer.
[21]
We gathered evidence that evaluated how morphology, age, and sex effects ocular cancer trend,
outcome and treatment.
2.3. Search strategy and study selection criteria
A systematic reviewing method was employed to garner the relevant literature for the research
objective. A detailed search strategy was developed and implemented to find all relevant
articles/texts. Appropriate inclusion and exclusion criteria were set to target and focus the
search (Table 1).
Search terms were found by running a scoping search and identify the relevant indexing terms
for relevant articles. The terms were modified according to electronic database being used. The
terms used is given in the table below (Table2).
The search method we used is searching and reviewing the Literature byMary Ebeling and Julie
Gibbs to search electronic database, Book, reference searching and hand searching
(Corwin.com, 2015).
Table 1: Inclusion & exclusion criteria.
1
2
3
4
5
Inclusion Criteria
Full text, English language and human
studies. Studies after 1990
Published literature/ grey literature
Primary aim of the study/ research
related to the topic- studies that primarily
focus on ocular cancer trends, incidence,
therapeutics, interventions and outcome.
Hospital/ population based studies
Studies that focus on morphology
associated with outcome, treatment and
recurrence.
[22]
Exclusion Criteria
Foreign language, non-human. Studies
before 1990
Primary aim of the study/ research not
related to the topic.
Case reports studies
Studies other than ocular cancer and
lymphoma.
2.4. Methods of searching the literature
We followed the search methods step by step. In addition to conventional searches of electronic
database (PubMed, Embase/Medline, Cocnarane library) searches of other electronic sources
were also conducted to locate relevant Irish based evidence for the literature. Google search
and oncology books were also searched.
Unrelated articles and journals came in search of these databases were firstly eliminated by
checking titles and abstracts using the inclusion criteria previously defined. Full texts of the
remaining studies were then obtained for further appraisal.
2.4.1 Electronic database searching
The three electronic databases listed were individually searched for relevant articles. Also
outlines the combinations of search terms used. Specific keywords, according to Boolean logic
principle, Mesh term, and search limitations methods were applied.
Table 2: Search terms used in advanced search of database.
Database
Strategy
#1
#2
Medline via PubMed
#1 AND #2
Eye
Retinoblastoma* OR Adenocarcinoma* OR Epithelioid cell melanoma*
OR Melanoma* OR Spindle cell melanoma* OR embryonal
Rhabdomyosarcoma* Melanoma NOS* OR mixed epithelioid and
spindle cell* OR Sarcoma* OR Squamous cell carcinoma
2.4.2. Book searching
Directly searching MD Anderson Manual of Medical Oncology 2011 (Kantarjian, Wolff and
Koller, 2011) and Clinical Radiation Oncology 3rd edition by Leonard L (Gunderson, Tepper
and Bogart, 2012). Gunderson Books for relevant material on Ocular neoplasm done.
[23]
2.4.3 Reference list searching
The reference lists of articles we searched for ocular neoplasm were cross-checked to identify
additional relevant articles for the review. The articles were also used to verify the validity of
the selected article.
Figure 1: Flow chart diagram for search strategy
Identified studies through electronic
database search with PubMed, Cochrane
Library, Medline and Google scholar
Information collected through
other sources
(n= 729)
Studies removed for
duplicate (n=182)
Studies remained with full article
(n=547)
Inclusion and
exclusion criteria
applied (n=385)
Articles with full text
(n=162)
Irrelevant articles and
removed (n=146)
Studies included in
literature review
(n=16) the studies
include two
systematic reviews
and one metaanalysis
NCRI, WHO, Melanoma
skin foundation, HSE, CSO.
Two books.
[24]
2.5. Literature data extraction and quality appraisal methods
The quality of the each paper included in this review was evaluated, using Critical Appraisal
Skills Programme (CASP) checklists established by Oxford University Public Health Resource
Unit (Critical Appraisal Skills Programme (CASP), 2015). The CASP toolkit allowed for
individual evaluation of the literature review. Weakness and strengths in every study also
determined. Table 3.
2.5.1. Table 3: Quality assessment summary
Title
Super
selective
ophthalmic
artery infusion
of melphalan
for intraocular
retinoblastoma
: preliminary
results from
140 treatments
(Venturi et al.,
2012).
Author
Design
Acta
Clinical trial
Ophthalmologi
ca
Scandinavica
Foundation
2012
Risk
of CHODICK, G
cataract
2009
extraction
among adult
retinoblastoma
survivors(Cho
dick, 2009)
Trilateral
retinoblastoma
: a systematic
review
and
meta-analysis
(de Jong et al.,
2014).
DE JONG, M.
C., KORS, W.
A.,
DE
GRAAF, P.,
CASTELIJNS,
J.
A.,
KIVELÄ, T.
AND MOLL,
A. C. 2014
Sampling
June 2008 to
October
2010,
38
patients (18
women, 20
men;
age
range at first
treatment, 7
months to 22
years) with
41 eyes with
retinoblastom
a
Retrospectiv Seven
e
cohort hundred fiftystudy
three subjects
(828
eyes)
were
available for
analysis for
an average of
32 years of
follow-up
a systematic 90
articles
review and with
174
metapatients
analysis
included in
the
metaanalysis.
[25]
Strength
Clinical
trial, good
follow up,
precise
estimation
of
outcome,
outcome
clearly
specified,
benefits
worth the
harms and
cost.
Cataract
extraction
as result.
Measuring
the
outcome.
32 years of
follow-up
Limitation
Nonrandom
ised
selection.
Exclusion
of
infiltrating
RB,
anterior
chamber
invasion,
glaucoma,
haemorrhag
e.
PRISMA
guidelines
in selectin
the
studies,
Good
statistical
methods
Lack
of
histopathol
ogical proof
of
the
disease in
some might
be a bias.
Lack of UV
ray
exposure
details,
work
related
effects
details.
Combined
proton beam
radiotherapy
and
transpupillary
thermotherapy
for large uveal
melanomas: a
randomized
study of 151
patients
(Desjardins et
al., 2006).
Effects
of
radiotherapy
on
uveal
melanomas
and adjacent
tissues
(Groenewald,
Konstantinidis
and Damato,
2012).
Desjardins,
Randomized
L.,Lumbroso- control trial
Le
Rouic,
2006
151 randomly
assigned
uveal
melanoma
between
February
1999 to April
2003
Clinical
trial,
38
months of
follow-up.
Randomis
ation. All
clinical
outcome
considered
.
Very less
follow-up
time, there
is
no
compare
group
or
study are
result
mentioned.
GROENEWA Review
LD,
C.,
KONSTANTI
NIDIS,
L.
AND
DAMATO, B
2012
57 Articles
have
been
reviewed for
outcome and
complication
s.
57
Articles,
all
complicati
ons,
effects,
dose limits
and
treatment
patterns
are
explained
8.7 years
of mean
follow-up.
Specified
and
pathologic
ally
documente
d lesions.
No
statistical
significanc
e
mentioned,
no detailed
report on
each
and
every study
given
Tumour
thickness
and orbital
involveme
nt proved
by
pathologic
al report.
Clear
outcome
measurem
ent.
Confoundin
g
factors
like age and
sex was not
mentioned.
Primary iris CONWAY, R. Retrospectiv
melanoma:
M
e
nondiagnostic
2001
comparative
features and
case series
outcome
of
conservative
surgical
treatment
(Conway,
2001).
51
cases
diagnosed as
iris
melanoma
and
was
treated with
local
resection
from 1980 –
2000
Orbital
exenteration in
95 cases of
primary
conjunctival
malignant
melanoma
(Paridaens et
al., 1994).
95
orbital
exentration
case
of
malignant
melanoma
PARIDAENS,
A.
D.,
MCCARTNE
Y, A. C.,
MINASSIAN,
D. C. AND
HUNGERFO
RD, J. L. 1994
Retrospectiv
e
clinicopathol
ogical study
[26]
Deals only
with
iris
melanoma.
Other than
surgical
methods
were
not
mentioned.
Rhabdomyosa
rcoma:
the
experience of
the pediatric
unit of Kasr
El-Aini Center
of Radiation
Oncology and
Nuclear
Medicine
(NEMROCK)
(from January
1992
to
January
200126(EL-AAL,
2006)
.
Plaque
radiotherapy
in
the
management
of
scleralinvasive
conjunctival
squamous cell
carcinoma: an
analysis of 15
eyes (Arepalli
et al., 2014).
Topical
mitomycin-C
for treatment
of partiallyexcised ocular
surface
squamous
neoplasia
(Rahimi et al.,
2015).
Screening for
Metastasis
From
Choroidal
Melanoma:
The
Collaborative
Ocular
Melanoma
Study Group
Report
Abd
El-Aal Retrospectiv
HH, Habib EE, e study
Mishrif MM.
55 paediatric
rhabdomyosa
rcoma
diagnosed
during
the
years 1992 to
2001
Risk stage
wise and
advanced
multidisciplinar
y
treatment
Small
sample size,
lack
of
generalisab
ility of the
treatment
because of
the cost.
AREPALLI,
Interventiona Interventiona
S., KALIKI, l case series
l case series
S., SHIELDS,
involving 15
C.
L.,
patients with
EMRICH, J.,
histopatholog
KOMARNIC
ically
KY, L. AND
confirmed
SHIELDS, J.
scleral and/or
A.
intraocular
2014
invasion of
SCC
Multiple
outcome
measurem
ents.
Hospital
based and
valid data.
Retrospecti
ve study.
Lack
of
good
statistical
methods.
RAHIMI, F., Clinical trial
ALIPOUR, F.,
GHAZIZADE
H HASHEMI,
H.
AND
HASHEMIAN
, M. 2009
Interventio
nal
prospectiv
e
study.
Proven
pathology.
A
good
statistical
measure.
Very less
number of
cases. No
comparativ
e
studies
have been
mentioned.
Prospectiv
e
longitudin
al study.
Valid
laboratory
methods.
No
alternative
methods
discussed
fo
sensitivity
and
specifcity.
Marie Diener- Prospective
West, Sandra longitudinal
M. Reynolds,
Donna
J.
Agugliaro,
Robert
Caldwell.
2004
[27]
17
pathologicall
y
proved
ocular
surface
squamous
cell
carcinoma
between 2004
– 2006
All the 2,320
patients
enrolled in
COMS trial
had
LFT
done
(Diener-West,
2004).
Uveal
melanoma in
relation
to
ultraviolet
light exposure
and
host
factors (Holly,
Aston
and
Char, 1990).
Sun exposure
predicts risk of
ocular
melanoma in
Australia
(Vajdic et al.,
2002).
Intermittent
and
chronic
ultraviolet
light exposure
and
uveal
melanoma: a
meta-analysis
(Shah et al.,
2005).
Epidemiology
of
ocular
surface
squamous
neoplasia in
Africa
(Gichuhi et al.,
2013).
Para
meningeal
rhabdomyosar
coma
in
paediatric age:
results of a
pooled
analysis from
North
HOLLY,
E. Case control
A., ASTON,
D. A. AND
CHAR, D. H.
407 cases of
melanoma
diagnoses
between 1978
and 1987, and
870 controls
Multiple
risk
factors,
good
statistical
analysis.
Nonrandom and
highly
selective
cases.
A
retrospectiv
e study.
VAJDIC, C.
M.,
KRICKER, A.,
GIBLIN, M.,
MCKENZIE,
J., AITKEN,
J., GILES, G.
G.
AND
ARMSTRON
G, B. K.
SHAH, C. P.,
WEIS,
E.,
LAJOUS, M.,
SHIELDS, J.
A.
AND
SHIELDS, C.
L
2005
Case control 290 clinically
study
diagnosed
melanoma
cases and 916
controls
Blinding,
Bias due to
prospectiv less study
e analysis, population.
confoundi
ng
are
included in
analysis.
MetaAnalysis
12
studies
which
provided
clear
odds
ratio a d
standard error
for
the
exposure and
outcome is
included.
Multiple
exposure,
free
of
bias, clear
analysis of
data.
GICHUHI, S.,
SAGOO, M.
S., WEISS, H.
A.
AND
BURTON, M.
J. 2013
Systematic
and
nonsystematic
review
A fixed effect
model with
HIV
and
smoking used
for
metaanalysis.
J.
H.
M. Pooled
Merks, G. L. analysis
De Salvo, C.
Bergeron, G.
Bisogno,
A.
De Paoli, A.
Ferrari, A. Rey
10 studies on
RMS
with
factors PM
involvement,
age,
size,
invasiveness,
nodes treated
with RT
2014
[28]
Only
12
studies
from 133
studies
considered.
No effort
was made
to get the
relevant
study
analysis
made.
Multiple
Lack
of
outcome,
exact study
HIV, UV method has
exposure, introduced
HPV,
a selection
smoking
bias.
all
discussed
K-M
Bias
in
methods,
selection of
multiple
studies.
outcome
and
exposure.
American and
European
cooperative
groups
(Parameninge
al
rhabdomyosar
coma
in
pediatric age:
results of a
pooled
analysis from
North
American and
European
cooperative
groups, 2014).
2.5.2. Summary and conclusion of the literature review
Ocular neoplasm is being studied from the year 1944 till now. Around 15,948 studies has been
done so far (Ncbi.nlm.nih.gov, 2015). Most of the studies are done with single case or with less
number of cases due to less prevalence. Meta-analysis is about melanoma and its risk factor
(UV) and the systematic review is about squamous cell carcinoma. None of the papers covers
the ocular neoplasm as whole. Meta-analysis gives an inconclusive evidence on melanoma with
UV rays.
A meta-analysis was conducted (2005) by Shah, C.P(Shah et al., 2005) discusses the exposures
like welding, outdoor leisure, birth latitude, and UV exposure with melanoma and found
positive welding (OR 2.05), and no significance (OR 1.37) with UV ray exposure and outdoor
leisure activity. There are many studies which correlates UV with skin melanoma and ocular
neoplasm with significant effect. Elizabeth A. Holly’s (Holly, Aston and Char, 1990) study on
uveal melanoma in relationship to ultraviolet light exposure and host factors found green, grey,
blue and hazel eye colour, north European skins, ability to tan, sun and welding burns, large
[29]
nevi are all risk factors for uveal melanoma. Claire M. Vajdic’s study(Vajdic et al., 2002) sun
exposure predicts risk of ocular melanoma in Australia found that choroidal and ciliary
melanoma are strong positive for prolonged sun exposure. The study is inconclusive for iris
and conjunctival melanoma. A D Paridaens study (Paridaens et al., 1994) orbital exenteration
in 95 cases of primary conjunctival malignant melanoma advocates exenteration should be
reserved as a palliative procedure for advanced stage of neoplastic disease. The study also
advocates surgery combined with chemotherapy and radiotherapy to preserve the globe. Marie
Diener-west (Diener-West, 2004) studied screening for metastasis from choroidal melanoma
for the liver metastasis. 2320 patients enrolled for COMS study in that 714 patients had
metastasis in that 675 died, he found that LFT is not sensitive enough to find the liver
metastasis. This study gives an over view about the metastasis and survival.
Systematic review(Gichuhi et al., 2013) (2013) by Gichuhi,s. focused on squamous cell
carcinoma and compared the age specific rates of various countries and discussed about the
risk factors such as HIV, smoking, and Human Papilloma Virus (HPV). HIV (OR= 6.17) and
direct day light exposure, outdoor occupation (OR=1.7) found to have strong association and
smoking 2 studies (OR= 1.4) had a comparatively weaker association than the other three. As
HIV is an immune compromising disease we could understand the squamous cell carcinoma is
associated with age and decreasing immunity. Arepalli S (Arepalli et al., 2014) studied the
plaque radiotherapy in the management of scleral-invasive conjunctival squamous cell
carcinoma and found out its effective in curing the disease and as an alternative for enucleation.
Brachytherapy and electron beam therapy are the radiotherapy methods used to treat SCC
successfully. Rahimi F (Rahimi et al., 2015) studied the effect of topical mitomycin-c for
treatment of partially excised ocular surface squamous neoplasm. The mitomycin-C had 94%
[30]
nonrecurrence for 41 months without any major side effects. For the SCC and OSSN first and
preferred choice of non-invasive is mitomycin-C.
Marcus C de jong (2014) systematic review and meta-analysis (de Jong et al., 2014) explains
the treatment advancement and increased survival after 1995 in the trilateral retinoblastoma. In
trilateral RB 5 year survival after treatment has increased from 6% to 57% because of
conventional and high dose chemotherapy with stem cell rescue. In this he has clearly stated
that none of the trilateral RB survived before 1995 due to lack of treatment. Carlo Venturi’s
study (Venturi et al., 2012) on super selective ophthalmic artery infusion of melphalan for
intraocular retinoblastoma also shows the advancement in treatment and administration and
survival. Chodick. C studied the risk of cataract extraction among adult retinoblastoma
survivors explains the same, out of 1729 RB cases diagnosed from 1914 to 1984 only 1,169
were alive. In this population due to radiotherapy 51 cataract extraction happened.
Pooled analysis(Parameningeal rhabdomyosarcoma in pediatric age: results of a pooled
analysis from North American and European cooperative groups, 2014) by J.H.M. Merks
(2014) on Para meningeal RMS in paediatric age with the North American and European
cooperative groups concentrated on the para meningeal involvement which is considered as
poor prognostic factor. 10 studies with radiotherapy for RMS was analysed for the event free
survival, and overall survival. Patients treated with radiotherapy had a good EFS (62.6) and OS
(66.2) compared with non RT treated respectively 40.8%. This study reinfused the use of
radiotherapy in RMS and also have shown a good prognosis in para meningeal involvement
patients if treated with radiotherapy. Kasr El-Aini centre of radiation oncology paediatric unit
treated 55 case of embryonal RMS with various regimes of chemotherapy and conventional
radiotherapy. Despite the advances in the therapy 30% of the cases experienced progression or
relapse.
[31]
Chapter 3
3. Data and Methodology
This secondary analysis for the thesis used the data from National Cancer Registry Ireland. The
data available was both population and individual based. The available data from the NCRI is
for the period 1994 to 2012. As the ocular cancer affects all the age group we got the data from
0 to death or till the end of the study (2012). Fixed pre-specified intervals (cohort –based
survival analysis), 1994-1997, 1998-2001, 2002-2005, 2006-2009 and 2009-2012, also the data
of the year of death ends at 2012 where used(Ncri.ie, 2015). WHO standard diagnostic tool
ICD used for ocular cancer (ICD10 code C69) also includes the sites (C690 Conjunctiva, C691
Cornea, C692 Retina, C693 Choroid, C694 Ciliary body, C695 Lacrimal gland and Duct, C696
Orbit and C699 Eye, unspecified.
3.1 NCRI background information
In 1991 Minister for health established the National Cancer Registry which was funded by the
Department of health. The board was set up to collect and record all cancer data and has been
on its work since 1994. The functions of the board were laid down in 1991 legislation which
came to amendment in 1996. Key duties of the board are as follows.
To identify, collect, record, classify store and analyse information regarding cancer
relating incidence and prevalence of Ireland.
To collect, classify, record and store information in relation to every newly diagnosed
cancer patients information in relation to the cancer.
To promote and facilitate collected data for approved research and in health planning
and management.
To annually publish registries activities
[32]
To advice, inform, assist the Minister in relation to cancer related aspects.
Cross border co-operation is done with Northern Ireland where the Cancer Registry is a
member of Ireland-Northern Ireland –National Cancer Institute Cancer Consortium. The
Cancer consortium was established in 1999 at the Stormont Parliament Building in Belfast. As
a joint effort the two registries announced the findings of the entire island of Ireland findings
on May 2001 which was the first All-Ireland Cancer Statistics report. The consortium also
published collaborative reports on September 2004 April 2009(Ncri.ie, 2015).
The National Cancer Registry Ireland has 52 staff members presently. Throughout the country
NCRI has 19 members and others are based at registry’s headquarters in Cork. The NCRI
collect a wide range of information for every new cancer case. Name, address, gender, date of
birth, socioeconomic status, cancer location, type, stage and the treatment received for the same
are collected. All the information’s are collected from the records maintained in the hospital
medical records. The death certificate is used to collect data in the event of mortality. Trained
Tumour Registration Officers (TROs) who are based in the hospital collect most of the data for
NCRI. This is an active data collection, and all new cases, registration details, patient
information’s and treatment details are collected. Hospital pathology report provides almost
85% of the information on cancer. Some of the hospitals provide electronic data to the registry.
[33]
3.2. Administrative structure
Figure 2: The governance structure of the National Cancer Registry Ireland is given below.
Department of Health
National Cancer Registry
Board
Director Dr Harry Comber
(Acting)
Corporate
services
Research &
analysis
Data management &
tumour registration
officers
[34]
Information
technology
3.3. Data collection and Management
National Cancer Registry Ireland collects population based data from the information
management unit at the Department of Health. The statistical information is collected from
Public Health Information System (PHIS). The data gives information of the population, age
group, and overall population of every county and Ireland as a whole. The registry uses the
age-specific population and computes the age-specific rates. The crude rats for the cancer is
also compute with the use of sum of age-specific population rather than using the overall
population. The PHIS and the health board uses the same sum of county populations. The NCRI
data are a few years behind because of many reason. Mostly all the case are identified within
12 months of the diagnostic date. As the cancers are diagnosed through various sources like
pathology report, X-rays, and scans, it takes long time to collect all report and put together to
get the accurate information. With the limited resources strict quality control measures are used
in collecting the information. The national cancer registry keeps Patients name and address to
track the patient if he attends other hospital, to know the outcome, and to identify the risk areas.
The cancer registry is an independent agency and do not share any information in any
circumstances (Ali, 2014).
Cancer Factsheets is a one page summary of statistics for each and every cancer which includes
the number of new cases, mortality rate for the cancer in Ireland. Presently 2009 to 2012 annual
average incidence and mortality is available. The factsheets are frequently updated and will be
available online (Ncri.ie, 2015).
The figure below shows how the NCRI collects the information, and the availability of data
sources can be seen.
[35]
Source: National Cancer Registry Ireland
Figure 3: availability of data sources of NCRI
[36]
3.4. Ethical aspects
Ethical approval was obtained from The Clinical Research Committee of the Cork Teaching
Hospitals, UCC on 14th of April 2015.
3.5. Data used for the analysis
The variables used for the study from the dataset for this analysis are as follows.
Table 4: Data used and description
Variable Name
Year
Sex
Survival time
Patients status
Age
Marital status
Smoking status
Presentation
Diagnostic method
Morphology type
Site of cancer
Affected side
Residue
Treatment
Recurrence
Prefix
YOI
SEX
SURV-time
Description
Year of incidence.
Gender (sex of patient) M= male F= female
Survival in days from date of diagnosis to
death or 31/12/2012 (whichever is earliest)
VITAL_STAT
2=dead, 1= alive (at the end of follow-up)
AGE_GP
Five year age group at diagnosis
MARITAL
Marital status of the patient: (M) Married, (D)
Divorced, (E) separated, (S) single (W)
widowed (Z) other and unknown.
SMOKER
Smoking status of the patient © current (N)
Never smoked, (X) Ex-Smoker, (Z) Unknown
PRES
Method of presentation (A) Autopsy, (C1)
Screening unspecified, (C2) Screening
organised, (I) incidental, (S) symptomatic, (Z)
unknown.
DIAG
Method of diagnosis (H) Histology, (L)
clinical ( R) Radiology (Z) unknown
MORP_TYPE
Morphological subtype.
ICD10
ICD10 cancer code.
SIDE
Eye affected (L=Left, R=Right, B= Bothe,
Z=Unknown)
RESIDUAL
Extent of the residual tumour after treatment
Surgery,
chemo, Type of treatment given.
radio
RECUR_time
Time in days from diagnosis to recurrence.
[37]
3.6. Data Cleaning
Dataset preparing for analysis
Year of incidence (YOI) all the 19 years divided into 5 groups 1994 to 1997 (1997),
1998 to 2001 (2001), 2002 to 2005 (2005), 2006 to 2009 (2009), and 2010 to 2012 the
last 3 years (2012).
Vital statistics (VITAL_STAT) was given as string variable so it was renamed as vital
and used. No change is made in the values (Ats.ucla.edu, 2015).
Sex was renamed as gender and Male (M) converted to 1, Female (F) converted to 2
and used.
Age group (AGE_GP) which was again a string variable renamed as age group. The
available content was in five years group which was combined and made three group
as 1 (0 to 29), 2 (30 to 59) and 3 (60 and above).
Marital status (MARITAL) string removed and changed to numerical value. Married as
1, Divorced as 2, Separated as 3, Single never married as 4, Widowed as 5 and unknown
as 6.
Smoker was again converted into numerical values Current smoker as 1, Never smoked
as 2, Ex-smoker as 3, and unknown as 4.
Presenting method PRES was divided into three category from six. Screening
unspecified and opportunistic as C, symptoms kept as it is and unknown and incidental
as Z. No case was in Autopsy, and organised screening so left as such.
Diagnostic methods were in 13 categories, which was made four all the laboratory
methods cytology, histology put in H, all clinical methods as L, all radiological methods
into R, and unknown as Z.
Morphological types (MORPH_TYPE) was given in their original names as
adenocarcinoma, squamous, melanoma and retinoblastoma. All that was changed to
[38]
numerical value and combined.
All melanomas of various types as category 1,
Retinoblastoma as 2 and all other negligible and unknown combined and named as 3.
Residual after treatment (RESIDUAL) no residue kept as same, all microscopic and
macroscopic residual named as 1 and unknown as X.
3.7. Descriptive statistics
In the descriptive statistics basic demographic information will be calculated using the data.
Age, sex, marital status, smoking habit, diagnostic method, presenting methods, treatment,
morphology, ICD10, sides, residual, treatment methods surgery, radiotherapy, and
chemotherapy all the frequencies will be calculated. A separate descriptive analysis will be
done with morphological type.
3.8. Analysis plan for the specific objectives
Data analysis was conducted using STATA version IC 13.0 (64-bits) software and the Excel
2013.
3.8.1 Objective 1
The main objective is to determine cancer incidence by age, as the risk of cancer increases
exponentially with the increasing age. Different population age group have different burden of
disease which cannot be represented be crude incidence rate. The age standardised is the true
representation of the burden of each age group. Age- standardised rate is a summary of that
age specific group rate using a standard population (Cso.ie, 2015). The age wise population for
each and every age group and every year was collected from the CSO website. Using the Stata
every year incidence, age group wise incidence and gender age group wise incidence was
computed. The calculation is a weighted average of age-specific rates (Iarc.fr, 2015).
[39]
Age-standardised rate (SR) = (SUM (ri * Pi))/SUM Pi
ri is the age-group specific rate for age group I in the population being studied.
Pi is the population of age group I in the standard population.
The result is always expressed as rate per 100,000 person-years.
Age group less than 30, 30 to 60 and above 60 are the groups to be computed. Age-standardized
rates for all the three age groups, in that male and female separate for each and every age group
and all this rates to be calculated for all the five year groups and tabulated. Every age group
population for every year was taken from CSO and added to get the desired population for our
age groups.
The same age standardised rates were also be computed for each and every morphology type,
for every age group and for both the sex. This gives the age standardised incidence rate for
each and every ocular cancer morphology for every year for every 100,000 population. The
age-standardised rates for every cancer for different age group will give an idea of the incidence
of the age group.
Excel will be used and the age standardised rates will be tabulated and graph will be made to
see the graphical representation of every morphology, age group, and gender and year wise
incidence. The graphical representation will give a clear idea about the incidence of each and
every year with all the parameters.
Age standardised rate will be calculated for <30, 30 to 60 and 60+ age group in total for the
years 1997, 2001, 2005, 2009, and 2012, again this will be divided into Male and female for
the same age group, the male and female will be further divided into morphology melanoma,
retinoblastoma and other ocular cancers. The same values will be transferred to excel and the
graph will be made as again as mentioned above and plotted.
[40]
3.8.2 Objective 2
The Kaplan-Meier estimate is also known as product limit estimator, is used to estimate the
survival function from life time data. The KM curve can take the censored data into account.
The survival analysis can evaluate the data by follow-up time rather than calendar time. The
KM curve can also provide the patients at risk so that we understand the time and the number
of patients.
In this analysis KM curve will be plotted for gender with the analysis time.
Second KM curve will be plotted against different age group.
A separate KM curve for the morphology type will be plotted to see the difference in survival.
And KM curve for smoking, ICD10 code, residual after treatment, age and morphology, and
gender and morphology will also be made to see the difference. For each and every KM curve
a Log rank test will be computed to see the difference between the groups observed and
estimated events. All the potential confounder for ocular cancer will be considered and a KM
curve will be plotted for each of them.
3.8.3 Objective 3
Cox Proportional Hazard models will be done to estimate the risk over time, to get the
proportional hazards. Age groups, smoking groups, marital status, morphology, ICD10 all will
be regressed separately to find the significant groups. A multivariate cox regression will also
be done with all the variables and will be fitted and interpreted. A table with every variable and
groups, with P-value and confidence interval and Hazard ratio will be produced.
[41]
Chapter 4
4 Results
4.1. Descriptive statistics
The population based data received from NCRI for the study had 861 individuals who had
ocular neoplasm. The period of study is 1994 to 2012 a total of 19 years. The population age
is 0 to death during the diagnosis to death. The basic demographic characteristics of the study
population were divided into five time periods (1994-1997, 1998-2001, 2002-2005, 2006-2009,
and 2010-2012) are presented below (table 5). The study population has been presented with
the factors sex, age group, marital status, smoking status, and morphology.
Table 5: Distribution of new Ocular Cancer cases in the Republic of Ireland (1994-2012)
by socio-demographic characteristics across five grouped time-periods
Years
19941997
No (%)
19982001
No (%)
20022005
No (%)
20062009
No (%)
20102012
No (%)
Total
78
(47.56%)
76
(47.50%)
110
(55.56%)
92
(50.00%)
84
(54.19%)
440
(51.10%)
86
(52.44%)
84
(52.50%)
88
(44.44%)
92
(50.00%)
71
(45.81%)
421
(48.90%)
16
(9.76%)
20
(12.50%)
18
(09.09%)
28
(15.22%)
23
(14.84%)
105
(12.20%)
30-60
59
(35.98%)
44
(27.50%)
73
(36.87%)
54
(29.35%)
49
(31.61%)
279
(32.40%)
>60
89
(54.27%)
96
(60.00%)
107
(54.04%)
102
(55.43%)
83
(53.55%)
477
(55.40%)
126
(76.83%)
119
(74.38%)
162
(81.82%)
142
(77.17%)
124
(80.00%)
673
(78.16%)
Patients
Gender
Male
Female
Age
< 30
Morphology
Melanoma
[42]
No (%)
Retinoblastoma
8 (4.88%)
13
(8.13%)
10
(5.05%)
16
(8.70%)
17
(10.97%)
64
(7.43%)
Other cancers
30
(18.29%)
28
(17.50%)
26
(13.13%)
26
(14.13%)
14
(90.3%)
124
(14.40%)
88
(53.66%)
81
(50.63%)
116
(58.59%)
84
(45.65%)
88
(56.77%)
457
(53.08%)
Divorced
0 (0.00%)
1 (0.63%)
1 (0.51%)
2 (1.09%)
3 (1.94%)
7 (0.81%)
Separated
2 (1.22%)
1 (0.63%)
4 (2.02%)
5 (2.72%)
1 (0.65%)
13
(1.51%)
Single (never 29
Married)
(17.68%)
31
(19.38%)
39
(19.70%)
52
(28.26%)
39
(25.16%)
Widowed
36
(21.95%)
29
(18.13%)
27
(13.64%)
22
(11.96%)
12
(7.74%)
9 (5.49%)
17
(10.63%)
11
(5.56%)
19
(10.33%)
12
(7.74%)
24
(15.00%)
.
34
(17.17%)
24
(13.04%)
13
(8.39%)
125
(14.52%)
71
(45.81%)
365
(42.39%)
19
(12.26%)
66
(7.67%)
52
(33.55%)
305
(35.42%)
Marital Status
Married
Unknown/other
Smoking Status
Current
30
(18.29%)
190
(22.07%)
126
(14.63%)
68
(7.90%)
Never smoked
78
(47.56%)
62
(38.75%)
Ex-Smoker
17
(10.37%)
10
(6.25%)
Unknown
39
(23.78%)
64
(40.00%)
79 (39.90) 75
(40.76%)
6 (3.03%)
14
79
(7.61%)
(39.90%)
71
(38.59%)
56
(34.15%)
74
(46.25%)
120
(60.61%)
141
(76.63)
143
(92.26%)
534
(62.02%)
108
(65.85%)
164
(19.05%)
86
(53.75%)
160
(18.58%)
78
(39.39%)
198
(23.00%)
43
(23.37%)
184
(21.37%)
12
(7.74%)
155
(18.00%)
327
(37.98%)
861
(100%)
Vital Statistics
Alive
Dead
Total
A total of 861 ocular cancer patients were diagnosed to have ocular neoplasm. Males 440
(51.10%), and females 421 (48.90%) and shares almost equally. Below 30 age group 105
(12.20%), the 30 to 60 years age group 279 (32.40%) and the above 60 age group amount for
[43]
more than half of the cases 447 (55.40%). Morphology type melanoma of all types’ accounts
for almost 80% of the study population 673 (78.16%), Retinoblastoma 64 (7.43%) and other
cancer 124 (14.40%). Smoking status unknown 305 (35.42%) and never smoked 365 (42.39%)
group share more the current smokers 125 (14.52%) and EX-smoker 66 (7.67%). Patient’s life
status shows a significant trend in the year groups. The death during the 1994-1997 is 108
(65%) at the end of the study during the years 2010 to 2012 it is only 12 (7.74%). Total patients
alive during the study period is 534 (62.02%) and dead (327 (37.98%).
Distribution of newly diagnosed cases during the study period has been divided according to
the morphology and given below (table 6). Melanomas (M-49.18% & F-50.82%) and
retinoblastoma (M-51.56% & F-48.44%) have almost equal gender population, the other ocular
cases males 76 (61.29%) and females (38.71%). In the age group above 60 population
melanoma 402 (59.73%) and the other cancers 75 (60.48%) were found. The retinoblastoma
all 64 cases are confined to less than 30 years age population. In particular all the
retinoblastomas were found to be in below 5 years of age group. Vital status in melanoma 409
(60.77%), retinoblastoma 63 (98.44%) and other cancers 62 (50.00%) were alive.
Table 6: Distribution of new specific morphologic types of ocular cancer cases in the
Republic of Ireland (1994-2012) by socio-demographic characteristics
Melanomas
No (%)
Retinoblastomas Others
No (%)
No (%)
Gender
Male
331 (49.18%) 33 (51.56%)
Female
342 (50.82%) 31 (48.44%)
Age
<30
21 (3.12%)
30-60
250 (37.15%) 0 (0.00%)
64 (100%)
[44]
Total
No (%)
76 (61.29%) 440
(51.10%)
48 (38.71%) 421
(48.90%)
20 (16.13%) 105
(12.20%)
29 (23.39%)
>60
402 (59.73%) 0 (0.00%)
75 (60.48%) 279
(32.40%)
477
(55.40%)
Vital Statistics
Alive
409 (60.77%) 63 (98.44%)
Dead
264 (39.23%) 1 (1.56%)
Marital Status
Married
410 (60.92%) 0 (0.00%)
Divorced
7 (1.04%)
0 (0.00%)
Separated
9 (1.34%)
0 (0.00%)
Single (never 94 (13.86%) 64 (100%)
Married)
Widowed
100 (14.86%) 0 (0.00%)
Unknown/other
53 (7.88%)
0 (0.00%)
62 (50.00%) 534
(62.02%)
62 (50.00%)
327
(37.98%)
47 (37.90%) 457
(53.08%)
0 (0.00%)
7 (0.81%)
4 (3.23%)
13 (1.51%)
32 (25.81%)
190
26 (20.97%) (22.07%)
15 (12.10%) 126
(14.63%)
68 (7.90%)
Smoking Status
Current
108 (16.05%) 0 (0.00%)
Never smoked
267 (39.67%) 57 (89.06%)
Ex-Smoker
59 (8.77%)
Unknown
239 (35.51%) 7 (10.94%)
59 (47.58%) 66 (7.67%)
673 (78.16%) 64 (7.43%)
305
(35.42%)
861 (100%)
Total
0 (0.00%)
17 (13.71%) 125
(14.52%)
41 (33.06%)
365
7 (5.65%)
(42.39%)
124
(14.40%)
Melanoma was found to be high in never smoked 267 (39.67%) and with unknown smoking
status 239 (35.51%).
Clinical Characteristics associated with the cancer morphology has been plotted below (Table
7). Anatomical site choroidal plexus 424 (63.00%) and ciliary body 166 (24.67%) amounts for
most of the melanoma cases. All the retinoblastoma 64 (100%) cases were confined to retina
[45]
alone. Other cancer morphology has a fair distribution in all sites more in conjunctiva 27
(21.77%) and lacrimal gland 28 (22.58%).
Table 7: Distribution of new specific morphologic types of ocular cancer cases in the
Republic of Ireland (1994-2012) by clinical characteristics
Melanomas
No (%)
Retinoblastomas
No (%)
Others
No (%)
Total
No (%)
Anatomic sites
Conjunctiva
36 (5.35%)
0 (0.00%)
27 (21.77%)
63 (7.32%)
Cornea
3 (0.45%)
0 (0.00%)
4 (3.23%)
7 (0.81%)
Retina
8 (1.19%)
64 (100%)
5 (4.03%)
77 (8.94%)
Choroid
424 (63.00%)
0 (0.00%)
22 (17.74%)
446 (51.80%)
Ciliary body
166 (24.67%)
0 (0.00%)
15 (12.10%)
181 (21.02%)
gland 0 (0.00%)
0 (0.00%)
3 (2.42%)
3 (0.35%)
8 (1.19%)
0 (0.00%)
28 (22.58%)
36 (4.18%)
28 (4.16%)
0 (0.00%)
20 (16.13%)
48 (5.57%)
3 (0.45%)
1 (1.56%)
0 (0.00%)
4 (0.46%)
607 (90.19%)
61 (95.31%)
99 (79.84%)
767 (89.08%)
Unknown
Diagnostic
Methods
Histology
63 (9.36%)
2 (3.13%)
25 (20.16%)
90 (10.45%)
421 (62.74%)
52 (81.25%)
61 (50.00%)
534 (62.31%)
Clinical
108 (16.10%)
8 (12.50%)
25 (20.49%)
141 (16.45%)
Radiology
135 (20.12%)
4 (6.25%)
19 (15.57%)
158 (18.44%)
Other
Treatment
Surgery
7 (1.04%)
0 (0.00%)
17 (13.93%)
24 (2.80%)
394 (58.54%)
53 (82.81%)
40 (32.26%)
487 (56.56%)
Chemotherapy
65 (9.66%)
28 (43.75%)
15 (12.10%)
108 (12.54%)
Lacrimal
& duct
Orbit
Eye unspecified
Presentation
Screening
(unorganised)
Symptomatic
[46]
Radiotherapy
204 (30.31%)
Residual after Rx
No residue
175 (32.29%)
Residue (micro
& Macro)
97 (17.90%)
Unknown
270 (49.82%)
Total
673 (78.16%)
3 (4.69%)
37 (29.84%)
244 (28.34%)
38 (70.37%)
17 (18.89%)
230 (33.53%)
4 (7.41%)
31 (34.44%)
132 (19.24%)
12 (22.22%)
64 (7.43%)
42 (46.67%)
124 (14.40%)
324 (47.23%)
861 (100%)
Most of the cases presented with symptoms 767 (89.08%) and none of the cases were found in
organised screening. Only four cases have been identified during opportunistic screening. Most
of the diagnosis were made by histological 534 (62.31%) findings, clinically 141 (16.45%) and
radiologically 158 (18.44%) were diagnosed. In total surgery 487 (56.56%), chemotherapy 108
(12.54%) and radiotherapy 244 (28.34%) performed as treatment. Combined therapy chemo
and surgery, radiotherapy surgery 67 (13.76%) were performed. Radiotherapy & chemotherapy
combined was performed in 43 patients. Some 15 patients have received all three modality of
treatment. After treatment histologically (micro and macroscopic) confirmed residual were
present in 132 (19.24%) cases, and in 324 (47.23%) cases residual could not be accessed.
4.2. Results for the specific objectives
4.2.1 Age-Standardized Incidence rates
Table 8: Age-Standardized Incidence Rates (per 100,000) of Total Ocular Cancer cases
in the Republic of Ireland (1994-2012) by age-groups across five grouped time-periods.
AGE
(in
years)
<30
30-60
>60
1994-1997
Rates/100,000
1998-2001
Rates/100,000
2002-2005
Rates/100,000
2006-2009
Rates/100,000
2010-2012
Rates/100,000
0.22
1.11
4.03
0.28
0.71
4.07
0.24
1.06
4.12
0.36
0.71
3.39
0.40
0.87
3.67
[47]
Age-Standardized incidence rates for total ocular cancer case by age group for the five grouped
time period is give above (Table 8). During the all grouped period above 60 year population
had a higher SR which is above 3.5 per 100,000 population. The above 60 age population is
four to eight times more likely to get ocular cancer than the other. The rates in <30 age group
have gone up from 0.22/100,000 in 1994-1997 to 0.40/100,000 in 2010-2012 (a relative
increase of 81%). In contrast in the rates in 30 to 60 years age group have declined from
1.11/100,000 in 1994-1997 to 0.87/100,000 in 2010-2012 (a relative decrease of 21%). The
rates in above 60 age group have declined from 4.03/100,000 in 1994-1997 to 3.67/100,000 (a
relative decrease of 9%).
Table 9: Age-Standardized Incidence Rates (per 100,000) of Total Ocular Cancer cases
in the Republic of Ireland (1994-2012) by gender across five grouped time-periods
GENDE
R
Men
women
1994-1997
Rates/100,00
0
1998-2001
Rates/100,00
0
2002-2005
Rates/100,00
0
2006-2009
Rates/100,00
0
2010-2012
Rates/100,00
0
1.08
1.18
1.00
1.07
1.04
1.30
1.01
1.01
1.23
1.04
Age-standardized incidence rate by gender for the grouped years plotted above (Table 9). The
rates in men have gone up from 1.08/100,000 in1994-1997 to 1.23/100,000 in 2010-2012 (a
relative increase of 13%). In contrast rates in women has gone down from 1.18/100,000 in
1994-1997 to 1.04/100,000 in 2010-2012 (a relative decline of 12%).
[48]
Table 10: Age-Standardized Incidence Rates (per 100,000) of Total Ocular Cancer cases
in the Republic of Ireland (1994-2012) by specific morphologic types across five grouped
time-periods
1994-1997
Rates/100,0
00
1998-2001
Rates/100,0
00
2002-2005
Rates/100,0
00
2006-2009
Rates/100,0
00
2010-2012
Rates/100,0
00
MORPHOLOG
Y
Melanoma
0.87
0.77
0.95
0.68
0.91
Retinoblastoma 0.06
0.06
0.06
0.09
0.12
Others*
0.21
0.18
0.15
0.14
0.10
Others*= Adenocarcinoma, Embryonal rhabdomyosarcoma, Sarcoma, Squamous cell
carcinoma and unspecified.
Morphology wise age-standardization rates for the ocular cancer is plotted below (Table 10).
Melanoma remains high with around 1 for 100,000 population during all the time period.
Retinoblastoma was the lowest in morphology which is 0.06 to 0.12 for 100,000 population.
Other cancers combined together age-standardized rate was around 0.1 for 100,000 population.
The rates in Melanoma have gone up from 0.87/100,000 in 1994-1997 to 0.91/100,000 in 20102012 (a relative increase of 4%). The rates in retinoblastoma have also gone up from
0.06/100,000 in 1994-1997 to 0.12/100,000 in 2010-2012 (a relative increase of 100%) it has
doubled. In contrast rates of other cancer have declined from 0.21/100,000 in 1994-1997 to
0.10/100,000 in 2010-2012 (a relative decrease of 52%).
Table 11: Age-Standardized Incidence Rates (per 100,000) of Melanoma cases in the
Republic of Ireland (1994-2012) by age-groups across five grouped time-periods
1994-1997
1998-2001
2002-2005
2006-2009
2010-2012
Rates/100,000 Rates/100,000 Rates/100,000 Rates/100,000 Rates/100,000
AGE (in
years)
<30
0.06
30-60
0.96
>60
3.22
0.07
0.60
3.30
0.04
0.94
3.62
[49]
0.09
0.66
2.82
0.05
0.83
3.27
Melanoma case specific age standardization rates for the grouped year for all age groups are
plotted above (Table 11). Above 60 age group have a higher incidence rate than the other two
groups and is almost three to four times higher than the 30 to 60 age group and is more than
50 times higher than the below 30 age group. Below 30 age group people incidence for the
given time is 0.06 for 100,000 population. During the given periods all the rates and age group
remained almost same with very little change.
Table 12: Age-Standardized Incidence Rates (per 100,000) of Melanoma cases in the
Republic of Ireland (1994-2012) by gender across five grouped time-periods
1994-1997
1998-2001
2002-2005
2006-2009
2010-2012
Rates/100,000 Rates/100,000 Rates/100,000 Rates/100,000 Rates/100,000
Gender
Men
women
0.79
0.94
0.65
0.87
1.00
0.91
0.76
0.80
1.02
0.79
Age-Standardized rates of melanoma gender wise given for the grouped time period given
above (Table 12). The Melanoma rates in men have gone up from 0.79/100,000 in 1994-1997
to 1.02 in 2010-2012 (a relative increase of 29%). In contrast the melanoma rates in female
have declined from 0.94/100,000 in 1994-1997 to 0.79/100,000 in 2010-2012 (a relative
decline of 16%).
Table 13: Age-Standardized Incidence Rates (per 100,000) of Retinoblastoma cases in the
Republic of Ireland (1994-2012) by age-groups across five grouped time-periods
1994-1997
1998-2001
2002-2005
2006-2009
2010-2012
Rates/100,000 Rates/100,000 Rates/100,000 Rates/100,000 Rates/100,000
AGE (in
years)
<30
0.11
30-60
0.00
>60
0.00
0.18
0.00
0.00
0.13
0.00
0.00
[50]
0.21
0.00
0.00
0.29
0.00
0.00
Retinoblastoma is a below five years disease and with the table given (Table 13) it is clear that
the other age groups 30-60 and above 60 is not affected. The retinoblastoma rates have gone
up from 0.11/100,000 in 1994-1997 to 0.29/100,000 in 2010-2012 (a relative increase of
163%).
Table 14: Age-Standardized Incidence Rates (per 100,000) of Retinoblastoma cases in the
Republic of Ireland (1994-2012) by gender across five grouped time-periods
1994-1997
1998-2001
2002-2005
2006-2009
2010-2012
Rates/100,000 Rates/100,000 Rates/100,000 Rates/100,000 Rates/100,000
Gender
Men
women
0.08
0.03
0.09
0.07
0.06
0.06
0.10
0.08
0.09
0.16
Retinoblastoma age-standardized rates by gender is given above (Table 14). The
retinoblastoma rates in men remained almost same during the all given years. In contrast the
women retinoblastoma rates have gone up from 0.03/100,000 in 1994-1997 to 0.16/100,000 in
2010-2012 (a relative increase of 433%).
4.2.2. Kaplan-Meier survival curve with cox proportional hazard analysis
Survival analysis was done with the same data and KM curves were plotted for variables of
significance and explained below. The study subject were 861 and 9 of them were dropped on
the day when they got diagnosed. The remained population was 852. During the study period
there was 318 deaths observed. The earliest observed was on the day 1 and the last observed
or the maximum time observed is 6937 days. The total analysis time for the study is 1956270
days. The cumulative incidence for the total tome period is 0.00016 and the median survival
time is 4552.
[51]
Ocular cancer incidence by gender
Kaplan-Meier survival curve of ocular cancer by gender plotted is given below (Figure 4). Male
and female do not have different chance of survival from ocular cancer (Log-rank test: χ2 =
0.12; p =0.73).
Figure 4: Kaplan-Meier of 1994-2012 Ocular Cancer cases by gender
0.00
0.25
0.50
0.75
1.00
Kaplan-Meier survival estimates by gender
0
Number at risk
gender = 0 419
gender = 1 433
2000
4000
analysis time in days
6000
8000
199
204
85
75
19
19
0
0
Female
[52]
Male
Ocular cancer by age groups
Km curve survival curve plotted for the different age group is given below (Figure-5). The
graph shows clear demarcation between the rates of survival amongst the three age-groups.
The below 30 age group shows significantly higher survival than the other two groups. The 3060 age group shows better chance of survival from ocular cancer than the above 60 age group.
The graph clearly shows that all the three age groups have different chance of survival. (Logrank test: χ2 = 94.39; p=0.00).
Kaplan-Meier survival estimates by age group
0.00
0.25
0.50
0.75
1.00
Figure 5: Kaplan-Meier of 1994-2012 Ocular Cancer cases by age-group
0
Number at risk
agegroup = 1 105
agegroup = 2 277
agegroup = 3 470
2000
4000
analysis time in days
6000
8000
55
152
196
33
72
55
10
19
9
0
0
0
<30 age
Above 60 age
[53]
30-60 age
Ocular cancer by morphology
The KM survival curve plotted against the morphological type is plotted below (Figure 6).
Retinoblastoma shows better survival than the other two groups. The curves of melanoma and
other cancers crosses in many areas, and the Log rank may not find the difference between the
groups (Log-rank test χ2 = 29.60; p=0.00). The cox regression model also indicates that
retinoblastoma (HR=0.03; CI= 0.00-0.23; p=0.00) has 97% better prognosis than the
melanoma, and the other cancers have 16% poor prognosis than Melanoma. From the graph it
is very clear the retinoblastoma has a very good survival and have only one death.
Kaplan-Meier survival estimates by morphology
0.00
0.25
0.50
0.75
1.00
Figure 6: Kaplan-Meier of 1994-2012 Ocular Cancer cases by morphologic types
0
Number at risk
type = 1 673
type = 2 64
type = 3 115
2000
4000
analysis time in days
6000
8000
317
33
53
115
22
23
25
6
7
0
0
0
Melanoma
Other cancers
[54]
Retinoblastoma
Ocular cancer by smoking status
The KM curve shows the survival estimates of ocular cancer by smoking status (Figure 7). The
graph shows the survival of EX-smoker and current smoker is poorer than other groups, and
the never smoker and unknown groups survival are almost similar (Log-rank test, χ2 = 8.83;
p=0.03) and the curve crosses in many place. The cox regression done with the smoking status
does not show any significant changes in between the groups (Table 15).
0.00 0.25 0.50 0.75 1.00
Figure 7: Kaplan-Meier of 1994-2012 Ocular Cancer cases by smoking status
Number at risk
SMOKER = 1
SMOKER = 2
SMOKER = 3
SMOKER = 4
Kaplan-Meier survival estimates bt smoking status
0
2000
4000
analysis time in days
6000
8000
124
365
66
297
63
170
23
147
23
72
9
56
6
19
3
10
0
0
0
0
Current
Ex-smoker
[55]
Never
Unknown
Ocular cancer by anatomical site (ICD10)
The KM curve shows the survival estimates by the involved sites according to ICD10
classification. From the graph it is clear that the retinal and ciliary body have a significantly
better survival than the other sites (Log-rank test χ2 =34.02; p=0.00). The cox regression run
also showed the same retina (HR=0.17; CI 0.07-0.39; p=0.00), Ciliary body (HR=0.64, CI
0.42-0.98; p=0.04) (Table 15). The death rates by ocular cancer site retina is 83% better than
conjunctiva, and the death rate from ciliary body is 36 % better than the conjunctiva.
Figure 8: Kaplan-Meier of 1994-2012 Ocular Cancer cases by anatomic sites (ICDs)
Conjunctiva
Cornea
Retina
Choroid
Ciliary body
Lacrimal Gland & duct
0.00
0.50
1.00
0.25
0.75
0.00
0.50
1.00
0.25
0.75
Kaplan-Meier survival estimates by sites (ICD10)
0
0.00
0.50
1.00
0.25
0.75
Orbit
0
2000
4000 6000
Eye, unspecified
8000 0
2000 4000
6000
analysis time in days
Graphs by ICD10
[56]
8000
2000
4000
6000 8000
Ocular cancer by year of incidence
The KM curve shows the survival estimate by year of incidence (Figure9). From the given
graph it is clear that all the year groups have similar survival (Log-rank test χ2 = 5.82; p=0.21).
The cox regression done with year of incidence shows a better survival for the 2006-2009 year
of incidence (HR=0.67; CI=0.45-0.97; p=0.04). The 2006-2009 year of incidence population
had a 33% better survival than the 1994-1997 group.
0.00 0.25 0.50 0.75 1.00
Figure 9: Kaplan-Meier of 1994-2012 Ocular Cancer cases by time-periods
Kaplan-Meier survival estimates by year of incidence
Number at risk
YOI = 1997
YOI = 2001
YOI = 2005
YOI = 2009
YOI = 2012
0
2000
4000
analysis time in days
6000
8000
162
155
197
183
155
106
107
144
46
0
75
82
3
0
0
38
0
0
0
0
0
0
0
0
0
YOI = 1994-1997
YOI = 2002-2005
YOI = 2010-2012
[57]
YOI = 1998-2001
YOI = 2006-2009
Ocular cancer by gender and age group
The KM curve shows the survival estimates of male and female of all the three age-groups
(Figure 10). From the graph it is clear the below 30 years of age have a good survival rates
than the other four groups. In that below 30 years male have slightly better survival than the
below 30 years female (Log-rank test χ2 =95.02; p=0.00). The cox regression also indicates the
same result. The 30 to 60 years age-group (HR=3.76; CI 1.81-7.79; p=0.00) had 3 times poor
survival and above 60 age group (HR=9.32; CI=4.60-18.90; p=0.00) had 9 time poor survival
than the below 30 years age-group.
Figure 10: Kaplan-Meier of 1994-2012 Ocular Cancer cases by gender and age-groups
0.00 0.25 0.50 0.75 1.00
0.00 0.25 0.50 0.75 1.00
Kaplan-Meier survival estimates gender & age-group
0
Female, <30 years
Female, 30-60 years
Female, 60+ age
Male, <30 years
Male, 30-60 years
Male, 60+ age
2000
4000 6000
8000 0
2000 4000
6000
analysis time in days
Graphs by gender and agegroup
[58]
8000 0
2000
4000
6000 8000
Ocular cancer by residual status
The KM curve shows the survival estimate by the state of residue after treatment (Figure 11).
From the graph it is clear that the group whom the residual status cannot be accessed has a poor
survival than the no residual group and residual group (Log-rank test χ2 =6.82; p=0.03). The
cox regression also shows significance for unknown residual status (HR=1.44; CI=1.06-1.95;
p= 0.02) which shows that the unknown residual status death rate is 44% higher than the no
residual group (Table 15).
Figure 11: Kaplan-Meier of 1994-2012 Ocular Cancer cases by residual
0.00
0.25
0.50
0.75
1.00
Kaplan-Meier survival estimates by residual
0
Number at risk
RESIDUAL = 0 230
RESIDUAL = 1 132
RESIDUAL = 2 323
2000
4000
analysis time in days
6000
8000
112
84
113
37
26
36
1
0
2
0
0
0
RESIDUAL = No residue
RESIDUAL = Unknown
[59]
RESIDUAL = Residue +
Ocular cancer by morphology and age group
The KM curve shows the survival estimates by morphology for every age group (Figure 12).
The graphs below clearly shows most of the groups are different form on another (Log-rank
test χ2 =121.36; p=0.00). Retinoblastoma under 30 years have a better prognosis than the other
all groups (HR=0.11; CI=0.01-0.96; p=0.46) in contrast the above 60 age group of melanoma
and other cancers have very poor prognosis (HR=4.99; CI=2.31-10.74; p=0.00). It is clear that
the above 60 age-group prognosis of any morphology is five times poorer than the below 30
age-group.
Figure 12: Kaplan-Meier of 1994-2012 specific morphologic ocular cancer cases by agegroups
Kaplan-Meier survival estimates by Morphology & age-group
Melanoma, 30-60 years
Melanoma, >60 years
Retinoblastoma, < 30 years
Other cancers, <30 years
Other cancers, 30-60 years
0.00
0.50
1.00
0.25
0.75
0.00
0.50
1.00
0.25
0.75
Melanoma, < 30 age
0.00
0.50
1.00
0.25
0.75
0
2000 4000
6000
Other cancers, > 60 years
0
2000
4000 6000
8000
analysis time in days
Graphs by type and agegroup
[60]
8000 0
2000
4000
6000 8000
Ocular cancer by morphology and gender
The KM curve shows the survival analysis by morphology and gender (Figure 13). Both male
and female retinoblastoma groups show better survival compared to the other groups (Logrank test χ2 =31.01; p=0.00). The cox regression done with morphology and gender also shows
that the retinoblastoma have a better prognosis than the other group (HR=0.03; CI=0.00-0.23;
p=0.00). It is clear the death rate of retinoblastoma is 97% better than the melanoma.
Figure 13: Kaplan-Meier of 1994-2012 specific morphologic ocular cancer cases by
gender
0.00 0.25 0.50 0.75 1.00
0.00 0.25 0.50 0.75 1.00
Kaplan-Meier survival estimates by morphology & gender
0
Melanoma, Female
Melanoma, Male
Retinoblastoma, Female
Retinoblastoma, Male
Other cancers, Female
Other cancers, Male
2000
4000 6000
8000 0
2000 4000
6000
analysis time in days
Graphs by type and gender
[61]
8000 0
2000
4000
6000 8000
Multivariable analysis
Univariate analysis and multivariate analysis has been done with the covariates to adjust the
potential confounding and fond the variable which is significantly associated with the survival.
In the univariate analysis the 30-60 age-group shows three times more risk as compared to
below 30 age group (HR=3.67; CI=1.81-7.79; P=0.00). The above 60 age-group is nine time
more risk than the below 30 age-group (HR=9.32; CI4.60-18.89; P=0.00). Never married group
showed 44% lower risk than the married group (HR=0.56; CI=0.40-0.78; P=0.00). The widow
group showed 63% higher risk than the married group (HR=1.63; CI=1.24-2.14; P=0.00). In
the cancer sites retina showed 83% lesser risk (HR=0.17; CI=0.08-0.39; P=0.00) and ciliary
body showed 36% lesser risk (HR=0.64; CI=0.42-0.98; P= 0.04) than the conjunctiva
involvement. The residual status which is unknown/ not able to access had 44% higher risk
(HR=1.44; CI=1.07-1.95; P=0.02) than the no residual group.
Table 15: Univariate and Multivariable Cox Proportional Hazards Regression analysis
with covariates
Covariates
Female
Male
< 30 age
30-60 age
> 60 age
Married
Divorced
Separated
Single
Widowed
Unknown
Current smoker
Never smoked
Ex-smoker
Unknown
Conjunctiva
Cornea
Retina
Univariate Analysis
HR (95%CI)
P- Value
Reference
0.96 (0.77-1.20)
0.73
Reference
3.76 (1.81-7.79)
0.00
9.32(4.60-18.89)
0.00
Reference
1.27 (0.31-5.13)
0.73
0.69 (0.25-1.85)
0.46
0.56 (0.40-0.78)
0.00
1.63 (1.24-2.14)
0.00
0.89 (0.55-1.45)
0.64
Reference
0.77 (0.56-1.05)
0.10
1.32 (0.85-2.05)
0.21
0.82 (0.60-1.14)
0.24
Reference
0.70 (0.21-2.29)
0.56
0.17 (0.08-0.39)
0.00
[62]
Multivariate analysis
HR (95% CI)
P-Value
0.94 (0.71-1.25)
0.69
1.74 (0.62-4.91)
4.90 (1.80-13.35)
0.29
0.00
1.36 (0.33-5.63)
0.67 (0.21-2021)
0.93 (0.60-1.44)
1.12 0.79-1.60
0.68 (0.37-1.24)
0.67
0.52
0.75
0.51
0.20
0.69 (0.46-1.03)
1.02 (0.58-1.80)
0.72 (0.48-1.06)
0.07
0.93
0.10
0.89 (0.25-3.10)
1.38 (0.55-3.44)
0.85
0.49
Choroid
Ciliary body
Lacrimal G&D
Orbit
Eye, unspecified
No residue
Residue present
Residue
unknown
0.91 (0.62-1.33)
0.64 (0.42-0.98)
1.53 (0.37-6.39)
0.99 (0.54-1.81)
1.23 (0.73-2.09)
Reference
1.06 (0.73-1.53)
1.44 (1.07-1.95)
0.63
0.04
0.56
0.99
0.43
1.11 (0.68-1.80)
0.76 (0.44-1.29)
Omitted
1.75 (0.77-3.97)
1.30 (0.65-2.57)
0.67
0.31
0.76
0.02
0.88 (0.60-1.29)
1.27 (0.93-1.75)
0.52
0.14
0.18
0.45
Multivariable analysis done and all the potential confounders adjusted and the results are shown
in the table (table 15). In this model only the age group above 60 have retained the effect, and
is still a potential risk factor for the survival and is five times more risk than the other age
groups (HR=4.90;CI =1.80-13.35, P-0.00). The proportional-hazards assumption done with the
above model (X2 (19) =14.36; P=0.76). This shows that the null hypothesis cannot be rejected
for this model of assumption.
[63]
Chapter 5
5. Discussion and conclusion
Discussion
The main aim of the study was to examine the age-standardized rates of ocular neoplasm and
the survival rates in the Republic of Ireland over 19 year period from 1994-2012 using the
National Cancer Registry Ireland (NCRI) incidence data. The data from NCRI had 861 ocular
cancer incident cases and (861+17) 878 (17 bilateral) eyes over a period of 19 years. The main
significant finding are:
1. The risk of death by ocular neoplasm was increased significantly (HR=9.32; CI=4.60-18.89;
p=0.00) with older age (above 60 years of age) compared to the 30 to 60 years of age group
and below 30 years of age group, implying that the risk is around 9 times higher than those
below 30 years of age.
2. Retinoblastoma, a genetic disorder has seen 100% increase in the age-standardized incidence
rate between 1994 and 2012. The rates in retinoblastoma have also gone up from 0.06/100,000
in 1994-1997 to 0.12/100,000 in 2010-2012 (a relative increase of 100%) it has doubled.
3. Ocular Melanoma in males has seen 29% increase from 0.79/100,000 in 1994-1997 to 1.02
in 2010-2012. Organised screening played no role in diagnosis of ocular cancers during the
given period. Ocular melanoma which is caused by prolonged exposure to ultra violet (UV)
rays contributes to almost 78% of all eye cancers in the Republic of Ireland. Ocular lymphoma
which is a disease mostly associated with immune deficiency and old age is not recorded in
found in Republic of Ireland during the 1994 and 2012.
Ocular cancer is always listed in the other cancers which occupies a least portion (less than
7%) of all cancers. Ocular cancer in advanced stages leads to loss of eye sight and loss of eye
[64]
ball and disfiguration. Recent research and treatment is aimed at preserving the sight and
anatomical structures, the same is discussed in this chapter in conclusion.
5.1. Retinoblastoma incidence
Retinoblastoma a child-hood disease, which affects the under 5 age- group population is a
genetic disorder which runs in family. In the NCRI data we have 64 proven retinoblastoma
cases during the period 1994-2012. Eight cases (4.88%) were recorded during the four years
from 1994-1997, which increased to 17 cases (10.97%) in 2010-2012. Overall the agestandardized retinoblastoma incidence rates increased from 0.06 for 100,000 population to 0.12
for 100,000 population in 2010-2012. A relative increase of 100% was noted during this 19
year period.
Age specific incidence rates of retinoblastoma cases were 0.11 cases for 100,000 in population
below 30 years age during 1994-1997 which increased to 0.29 for 100,000 during 2010-2012
years, a relative increase of 163% was noted in the below 30 age group population. As the
retinoblastoma is highly confined to below 5 years of age group if calculated for the age group
the incidence will be higher than this. Worldwide, the cumulative lifetime incidence rate of
retinoblastoma is 1 per 18000 to 30000 live births (ABRAMSON and SCHEFLER, 2004).
Most of the children lose their sight and eyeball as it involves retina-a vital site for vision.
5.2. Ocular Melanoma Incidence
Ocular melanoma is associated with the Ultra Violet (UV) radiation, time of stay outside,
occupations like welding and heat. Scandinavian countries have a higher risk of melanoma
compared to other countries. North European skin colour, blue and light Iris, navies, and ability
to tan are considered risk factors for melanoma. In United States the incidence is reported as
0.5 for 100,000 population where as in Europe it is 0.7 for 100,000 population
(Ocularmelanoma.org, 2015). In United Kingdom 70% of all eye cancer is melanoma during
[65]
the year 2000 (Huerta, 2001). In Africa the incidence is around 0.02-0.04 per 100,000
population and in Asia it is 0.01 for 100,000 population (Futuremedicine.com, 2015). Uveal
melanoma incidence in United States among various race during 1992-2000 0.03 (black), 0.03
(Asian), 0.16 (Hispanic), and 0.6 (non-Hispanic white) per 100,000 population (Hu et al.,
2005). In Ireland 78 % of all ocular cancers are melanoma, and the standardized rates stay
between 0.68 and 0.91 per 100,000 population in the given time period 1994 and 2012. The
result proves the Irish (non-Hispanics) in United States are also more prone for ocular
melanoma. Older age group (above 60 years of age) are four times prone to ocular melanoma
than the adult population (30-60 years of age). Age standardized rates remain around 2.28-3.62
for 100,000 above 60 years population during the years 1994-2012. Whereas for the 30-60
years population the standardized rates remained around 0.60-0.96 for 100,000 population.
5.3. Ocular melanoma and Gender
During the study period 673 melanoma cases where noted in that 331 (49.18%) males and 342
(50.82%) females. From the given years melanoma in men have gone up from 0.79 for 100,000
population to 1.02 for 100,000 population, whereas in female it have gone down from 0.94 for
100,000 population to 0.79 for 100,000 population in the years 1994-2012. There is a relative
increase of 29% in male melanoma incidence and a 16% decrease in female melanoma
incidence in the study years (1994-2012). Worldwide the same is noted in the gender, an
increase in male ocular melanoma incidence and decreased female melanoma incidence.
5.4. Screening and ocular cancer
Presentation of ocular cancer to the hospital or to GPs was also studied with the data provided
by NCRI. Of the total 861 cases, 767 (89%) of the cases reported to the hospital after the
symptoms appear (90% melanoma 95% retinoblastoma, and 79% other cancers). Only one of
64 retinoblastoma was identified in unorganised screening. Unorganised screening
[66]
(opportunistic and screening for other purpose) have found 4 cases (0.46%) cases in the 19
years. Ocular specific screening has found no cases during the study period 1994-2012. Early
diagnosis of ocular cancer can prevent visual loss, and eye ball (Eyewiki.aao.org, 2015). In
United States all neonates have been screened for retinoblastoma as a routine practise to
prevent patients losing the eye ball (enucleation). In advanced ocular cases enucleation is
performed to prevent the spread of cancer and as a treatment of choice, which leaves a
permanent disfiguration and psychological effect.
The American Academy of Paediatrics
recommends red reflex examination in neonates, infants and children before discharge and
during all subsequent routine health visits (Aapos.org, 2015).
5.5. Ocular cancer survival rate by morphology
Survival rates in melanoma and other cancers are poor than the retinoblastoma (figure 6). In
total 64 retinoblastoma cases only one died and all the 63 are alive. The log rank run with
morphology shows the same that there is difference in survival between morphological
subtypes. (χ2 =29.60; p=0.00). In cox regression the retinoblastoma survival is 93% (HR=0.03;
CI=0.00-0.23; p=0.00) better than melanoma, and the other cancers are 16% poorer than the
melanoma. Worldwide the survival of retinoblastoma is around 95% and in Ireland it is 98.44%
during the study period 1994-2012.
5.6. Ocular cancer survival rates by age-group
Ocular cancer risk of survival increases by age, overall. In the below 30 years age group,
92.38% were alive, in 30-60 years age-group 71.68% were alive and in above 60 years of age
group 49.69% were alive. Below 30 years of age, the survival is best compared to those who
were older (Log-rank test χ2= 94.39; p=0.00). Ocular cancer survival is poorer in the 30-60
(HR=3.76; CI=1.81-7.79; p=0.00) and above 60 age group (HR=9.32; CI=4.60-18.89; p=0.00).
[67]
Age group 30-60 years are 4 time more in survival risk than below 30 years of age and the
above 60 years age group are 9 time more riskier than the below 30 years of age group.
5.7. Strengths and limitations of the study
This is the first study to identify the survival rate of ocular cancer in the Irish population for
maximum of a 19 years follow-up period 1994-2012., using the most comprehensive nationally
representative ocular cancer data in Ireland. Morphology wise analysis is one of the strengths
of the study. Morphology wise age-standardized incidence and survival analysis was done for
a better understanding.
The main limitation of this study is the lack of information on staging, loss of sight and loss of
eyeball in the data. The study is a secondary analysis and the lack the information on
employment (UV) exposure. One of the other limitations is the small number of cases each
year that precludes from undertaking robust statistical modelling techniques.
5.8. Implication for public health policy and recommendations for the future
Ocular cancer public health policy has two dimensions according to morphology.
Screening for retinoblastoma which is a very easy procedure can be implemented by the
government as per The American Academy of paediatrician’s recommendations. Every child
who visit GP, and hospital should be examined for retinoblastoma and risk group screening
should be organised and genetic tests to be conducted.
Public health policy in melanoma should involve, weather report, news channels and
government agencies and screening. Government should warn people of using artificial
tanners. Whether reports and news should have the UV index of the day and warnings.
Screening should be organised for the individuals with blue iris, light skin and excessive navies
in the body.
[68]
Furthermore studies should be done on county level UV levels and melanoma incidence. For
retinoblastoma there should be studies on the genetic factors and genetic matching before
childbirth for high risk individuals.
5.9. Conclusions
These detailed population-based results of the Republic of Ireland found some interesting facts
of ocular cancer incidence and survival rate. We found there is an increase in male ocular
melanoma incidence between the years 1994-2012 with no good explanations. Likewise we
found a 100% increase in retinoblastoma incidence, again with no good explanation. Survival
rates in older age group is poorer than the adult and younger population during the years 19942012.
Further research is needed in the field of retinoblastoma and Male ocular melanoma as there is
a significant increase in incidence rates. Screening in under five age for retinoblastoma should
also be studied for its effect on preventing loss of vision and eye ball. Awareness should be
created on artificial tanning and UV in ocular melanoma prevention.
[69]
Chapter 6
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7. Appendices
Appendix 1:
CASP toolkits used for critical appraisal and quality assessment of each study included in the
literature review section.
1. Appraisal tool for clinical trial
2. Appraisal tool for systematic reviews
3. Appraisal tool for cohort studies.
CRITICAL APPRISAL SKILLS PROGRAMME
Making sense of evidence
11 questions to help you make sense of a trial
How to use this appraisal tool
Three broad issues need to be considered when appraising the report of a randomised controlled
trial:
Are the results of the trial valid?
What are the results?
Will the results help locally?
The 11 questions on the following pages are designed to help you think about these issues
systematically. The first two questions are screening questions and can be answered quickly.
If the answer to both is yes, it is worth proceeding with the remaining questions. There is some
degree of overlap between the questions, you are asked to record a yes, no or can’t tell to most
of the questions. A number of prompts are given after each question. These are designed to
remind you why the question is important. Record your reasons for your answers in the spaces
provided
Screening Questions
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Consider: An issue can be ‘focused’ In terms of
The population studied
The intervention given
The comparator given
The outcomes considered
randomised?
Consider:
How was this carried out, some methods
may produce broken allocation concealment
Was the allocation concealed from researchers?
Detailed questions
personnel blinded?
Consider:
Health workers could be; clinicians, nurses etc
Study personnel – especially outcome assessors
Consider: Look at
Other factors that might affect the outcome such as age,
sex, social class, these may be called baseline characteristics
5. A
were the groups treated equally?
the trial properly accounted for at its
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conclusion?
Consider:
Was the trial stopped early?
Were patients analysed in the groups to which
they were randomised?
7. How large was the treatment effect?
Consider:
What outcomes were measured?
Is the primary outcome clearly specified?
What results were found for each outcome?
Is there evidence of selective reporting of outcomes?
8. How precise was the estimate of the
treatment effect?
Consider:
What are the confidence limits?
Were they statistically significant?
(or to the local population?)
Consider:
Do you have reason to believe that your population
of interest is different to that in the trial
If so, in what way?
considered?
Consider:
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Is there other information you would like to have seen?
Was the need for this trial clearly described?
Consider:
Even if this is not addressed by the trial,
what do you think?
Making sense of evidence
10 questions to help you make sense of a review
How to use this appraisal tool Three broad issues need to be considered when appraising the
report of a systematic review: • Are the results of the review valid? (Section A) • What are the
results? (Section B) • Will the results help locally? (Section C) The 10 questions on the
following pages are designed to help you think about these issues systematically. The first two
questions are screening questions and can be answered quickly. If the answer to both is “yes”,
it is worth proceeding with the remaining questions. There is some degree of overlap between
the questions, you are asked to record a “yes”, “no” or “can’t tell” to most of the questions. A
number of prompts are given after each question. These are designed to remind you why the
question is important. Record your reasons for your answers in the spaces provided.
Screening Questions
HINT: An issue can be ‘focused’ In terms of
• The population studied
• The intervention given
• The outcome considered
HINT: ‘The best sort of studies’ would
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• Addressthe reviews question
• Have an appropriate study design (usually RCTs for
papers evaluating interventions)
Detailed questions
studies were included?
HINT: Look for
• Which bibliographic databases were used
• Follow up from reference lists
• Personal contact with experts
• Search for unpublished as well as published studies
• Search for non-English language studies
the quality of the included studies?
HINT: The authors need to consider the rigour of the studiesthey have
identified. Lack of rigour may affect the studies’ results. (“All that
glistersis not gold” Merchant of Venice – Act II Scene 7)
was it reasonable to do so?
HINT: Consider whether
• The results were similar from study to study
• The results of all the included studies are clearly displayed
• The results of the different studies are similar
• The reasonsfor any variations in results are discussed
6. What are the overall results of the review?
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HINT: Consider
• If you are clear about the review’s‘bottom line’ results
• What these are (numerically if appropriate)
• How were the results expressed (NNT, odds ratio etc
7. How precise are the results?
HINT: Look at the confidence intervals, if given
HINT: Consider whether
• The patients covered by the review could be
sufficiently different to your population to cause concern
• Your local setting is likely to differ much from that of the review
HINT: Consider whether
• Is there other information you would like to have seen
HINT: Consider
• Even if this is not addressed by the review,
what do you think?
Making sense of evidence
12 questions to help you make sense of cohort study
How to use this appraisal tool Three broad issues need to be considered when appraising a
cohort study: Are the results of the study valid? (Section A) What are the results? (Section
B) Will the results help locally? (Section C) The 12 questions on the following pages are
designed to help you think about these issues systematically. The first two questions are
screening questions and can be answered quickly. If the answer to both is “yes”, it is worth
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proceeding with the remaining questions. There is some degree of overlap between the
questions, you are asked to record a “yes”, “no” or “can’t tell” to most of the questions. A
number of italicised prompts are given after each question. These are designed to remind you
why the question is important. Record your reasons for your answers in the spaces provided
Screening Questions
1. Did the stud
HINT: A question can be ‘focused’ In terms of
The population studied
The risk factors studied
The outcomes considered
Is it clear whether the study tried to detect a beneficial or harmful effect?
HINT: Look for selection bias which might compromise
the generalisibility of the findings:
Was the cohort representative of a defined population?
Was there something special about the cohort?
Was everybody included who should have been included?
Detailed questions
minimise bias?
HINT: Look for measurement or classification bias:
Did they use subjective or objective measurements?
Do the measurements truly reflect what you want them to (have they been validated)?
Were all the subjects classified into exposure groups using the same procedure
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minimise bias?
HINT: Look for measurement or classification bias:
Did they use subjective or objective measurements?
Do the measures truly reflect what you want them to (have they been validated)?
Has a reliable system been established for detecting all the cases (for measuring disease
occurrence)?
Were the measurement methods similar in the different groups?
Were the subjects and/or the outcome assessor blinded to exposure (does this matter)?
confounding factors?
List the ones you think might be
important, that the author missed.
confounding factors in the design
and/or analysis? List:
enough?
enough?
7. What are the results of this study?
HINT: Consider
What are the bottom line results?
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Have they reported the rate or the proportion between the exposed/unexposed, the
ratio/the rate difference?
How strong is the association between exposure and outcome (RR,)?
What is the absolute risk reduction (ARR)?
8. How precise are the results?
HINT: Look for the range of the confidence intervals, if given.
9. Do you believe the results?
HINT: Consider
Big effect is hard to ignore!
Can it be due to bias, chance or confounding?
Are the design and methods of this study sufficiently flawed to make the results
unreliable?
Bradford Hills criteria (e.g. time sequence, dose-response gradient, biological
plausibility, consistency)
HINT: Consider whether
A cohort study was the appropriate method to answer this question
The subjects covered in this study could be sufficiently different from your population
to cause concern
Your local setting is likely to differ much from that of the study
You can quantify the local benefits and harms
available evidence?
12. What are the implications of this study for practice?
HINT: Consider
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One observational study rarely provides sufficiently robust evidence to recommend
changes to clinical practice or within health policy decision making
For certain questions observational studies provide the only evidence
Recommendations from observational studies are always stronger when supported by
other evidence
[85]
Appendices 2
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