Jonas Ranstam
Lund University, Department of Clinical Science, Lund, Department Member
Research Interests:
Research Interests:
Research Interests:
We are entering a new era with governmental bodies taking an increasingly guiding role, gaining control of registries, demanding direct access with release of open public information for quality comparisons between hospitals. This review... more
We are entering a new era with governmental bodies taking an increasingly guiding role, gaining control of registries, demanding direct access with release of open public information for quality comparisons between hospitals. This review is written by physicians and scientists who have worked with the Swedish Knee Arthroplasty Register (SKAR) periodically since it began. It reviews the history of the register and describes the methods used and lessons learned. Cite this article: Bone Joint Res 2014;3:217-22.
The results of a treatment method on adenocarcinoma corpus uteri stage I-II based upon cytometrically measured DNA ploidy are presented. All patients had a simple hysterectomy. Adjuvant treatment (postoperative vaginal brachytherapy) were... more
The results of a treatment method on adenocarcinoma corpus uteri stage I-II based upon cytometrically measured DNA ploidy are presented. All patients had a simple hysterectomy. Adjuvant treatment (postoperative vaginal brachytherapy) were given only to those patients with non-diploid tumours regardless of stage and grade. A total of 1,634 women with endometroid adenocarcinoma corpus uteri stage I-II were included where 1,396 patients were followed-up for at least 5 years or until death and the remaining 238 patients were followed-up 3.5-5 years or until death. By using cytometry only, we identified a low-risk group comprising 83% of the patients (with 5.2% dead from their disease) and a high-risk group of 17% (with 15.7% dead from their disease). By using grade only (well- and moderately differentiated vs poorly differentiated), the low-risk group comprised 87% of the patients (with 4.6% dead from their disease) and the high-risk group 13% (with 13% dead from their disease). By usin...
Research Interests: Pathology, Cancer, Brachytherapy, Treatment, Treatment Outcome, and 7 moreDNA, Humans, Female, Hysterectomy, Anticancer, Ploidy, and Ovariectomy
Research Interests:
Research Interests:
Research Interests:
Research Interests:
To estimate endometrial thickness by transvaginal ultrasound technique (TVU) in patients treated with tamoxifen; and to compare the results with hysteroscopy and directed biopsy, and to relate the findings to curettage material.... more
To estimate endometrial thickness by transvaginal ultrasound technique (TVU) in patients treated with tamoxifen; and to compare the results with hysteroscopy and directed biopsy, and to relate the findings to curettage material. Fifty-four women, over 50 years of age at the time of their primary breast cancer operation and scheduled for adjuvant treatment of tamoxifen, were investigated. If the endometrium measured 8 mm or more (35 patients) hysteroscopy and directed biopsy was performed. In the 35 patients, hysteroscopy and curretage revealed polyps in 18 cases (51.4%), proliferation in 1 case (2.9%) and atrophy in 16 cases (45.7%). In 54.3% (19 cases) of the patients the histopathological finding was a polyp or benign proliferation of the endometrium in agreement with the thickened endometrium seen with TVU. In the remaining 45.7% (16 cases) of the patients a thickened endometrium by transvaginal ultrasound was false positive as the hysteroscopic and subsequent histopathological d...
Research Interests: Treatment, Ultrasound, Biopsy, Humans, Female, and 10 morePolyps, Follow-up studies, Hysteroscopy, Anticancer, Vagina, Tamoxifen, Middle Aged, Adult, Utero, and Endometrium
Endometrial thickness as measured by ultrasound during tamoxifen treatment has previously been reported. However, there has not been any study investigating endometrial thickness before treatment and following it at regular intervals... more
Endometrial thickness as measured by ultrasound during tamoxifen treatment has previously been reported. However, there has not been any study investigating endometrial thickness before treatment and following it at regular intervals during treatment. 90 patients with breast cancer without any gynecological symptoms were followed (aged more than 50 years at the operation of their breast cancer). They were investigated by vaginal ultrasound and a common clinical investigation at our out-care patient department. Adjuvant breast cancer therapy consisted of tamoxifen, tamoxifen after radiotherapy and/or in a few cases cytostatics, cytostatics with or without the addition of radiotherapy, radiotherapy or no further therapy. Patients with receptor positive tumours were given tamoxifen. Their endometrium was already thicker before the start of adjuvant treatment as measured by ultrasound. After 3 months and 12 months we found the endometrium to be significantly thicker in those treated wit...
Research Interests:
The aim of the present investigation was to see if alternative histopathological parameters could identify a smaller high risk group than commonly seen using routine histopathological parameters. The material consisted of 150 primary... more
The aim of the present investigation was to see if alternative histopathological parameters could identify a smaller high risk group than commonly seen using routine histopathological parameters. The material consisted of 150 primary resected patients of FIGO Ia-Ic diagnosed as endometrial carcinoma and 12 cases of atypical hyperplasias which were suspected to contain small areas of carcinoma. The patients were treated from December 1979 to April 1993 at the Department of Obstetrics and Gynecology, University Hospital, Lund, Sweden. Those with deep myometrial invasion (> 50%) were given external radiotherapy (20-30 Gy) postoperatively. The follow-up period ranged from 2.5 to 5 years with 116 patients followed-up for more than 5 years. As no therapy was given before surgery we could investigate histopathologic variables such as degree of differentiation and cytology, number of mitoses per high power field (x 40), nuclear polymorphism, mode of invasion, the extension of myometrial ...
Research Interests:
To analyse the outcome of selective management of patients with abdominal aortic aneurysms, the expansion patterns of the aneurysms, and the factors that influenced the rate of rupture. Retrospective study. Malmö General Hospital, Lund... more
To analyse the outcome of selective management of patients with abdominal aortic aneurysms, the expansion patterns of the aneurysms, and the factors that influenced the rate of rupture. Retrospective study. Malmö General Hospital, Lund University, Malmö, Sweden. 155 patients (96 men and 59 women) with abdominal aortic aneurysms who were not selected for operation for whatever reason were included in the study immediately after their first ultrasound scan. Mortality, expansion rate (mm/year) measured on ultrasound scan, and rate of rupture of aneurysm. Median aneurysmal diameter was 40 mm (range 20-80), and length (n = 106) 70 (range 28-140). The patients were followed up for a median of 3.4 years (range 0-10.2). A total of 107 patients died and in 21 the aneurysms ruptured (4 were operated on and survived). Thirteen patients were re-evaluated and operated on electively. Ultrasonography was repeated in 98 patients, the median expansion rates (mm/year) were 3.1 (diameter) and 1.9 (len...
Research Interests:
Treatment of endometrial carcinoma has not improved during the last decades, due to the already good results. Such therapy has been a compromise, strong enough to cure some of those in need of harder treatment, but weak enough not to... more
Treatment of endometrial carcinoma has not improved during the last decades, due to the already good results. Such therapy has been a compromise, strong enough to cure some of those in need of harder treatment, but weak enough not to cause too severe side-effects. One way of solving the problem of overtreatment is to identify those in real need of a harder regimen. Generally, the histopathologic picture and the depth of myometrial invasion of the tumour have been used. However, this often means a too large high-risk group, often exceeding 50% of the patients. Steroid receptor concentrations and later DNA-measurements have been increasingly used to identify high-risk groups not, however, in combination. In 156 patients with endometrial carcinoma, both estradiol receptor concentration and flow cytometrically estimated DNA content were measured on all patients and the patients were followed-up for over five years. By using the number of DNA-populations (ploidy) we could identify a smal...
Research Interests: Flow Cytometry, Cell Differentiation, Humans, Female, Confidence intervals, and 15 moreFollow-up studies, Risk factors, Anticancer, Aged, Middle Aged, Neoplasm Invasiveness, Adult, Analysis of Variance, Time Factors, Prognosis, Age Factors, Risk Factors, Diploidy, Proportional Hazards Models, and Predictive value of tests
In a population-based group of women, consecutively diagnosed, with premenopausal breast cancer there was a significant correlation between tumour size and plasma prolactin (r = 0.30; P less than 0.004). The concentration of estrogen... more
In a population-based group of women, consecutively diagnosed, with premenopausal breast cancer there was a significant correlation between tumour size and plasma prolactin (r = 0.30; P less than 0.004). The concentration of estrogen receptor was negatively correlated to tumour size (r = 0.17; P less than 0.09). There were no substantial correlations between tumour size and progesterone receptor, plasma progesterone or estradiol. Adjustments for menstrual cycle day and age did not alter the above findings. The ratio of plasma prolactin and estrogen receptor was significantly greater (P less than 0.037) for the group of the patients that had started using oral contraceptives before the age of 20 as compared with the other patients. Consequently, the tumour size was significantly greater in the group of early users (P less than 0.003). The findings indicate that breast tumours developing in previous early users of oral contraceptives have a low estrogen receptor concentration, while t...
Research Interests:
In 65 young women undergoing curettage for benign uterine disorders a significant relationship was found between early oral contraceptive use (starting age less than 25 years) and a high ratio of ln plasma prolactin versus ln estrogen... more
In 65 young women undergoing curettage for benign uterine disorders a significant relationship was found between early oral contraceptive use (starting age less than 25 years) and a high ratio of ln plasma prolactin versus ln estrogen receptor concentration of the uterine mucosae (p less than 0.047, Mann-Whitneys U-test). Year of birth, age at menarche, age at first full term pregnancy, parity, menstrual cycle phase and duration of oral contraceptive use could not explain the results. Because similar results have previously been found for breast cancer patients using plasma prolactin and breast tumour estrogen receptor concentration, the findings indicate that early oral contraceptive use permanently alters plasma prolactin levels and estrogen receptor concentration, both in benign uterine tissue and in malignant breast tumours.
Research Interests: Physiology, Surgery, Cancer, Biology, Treatment, and 24 moreMembrane Proteins, Health, Menstruation, Public Health, Medicine, Safety, Side Effects, Population, Humans, Prolactin, Puberty, Female, Hormones, Hormone receptors, Anticancer, Middle Aged, Developed Countries, Adult, Genitalia, The Endocrine System Function, Age Factors, Parity, Uterus, and Urogenital System
The survival of 193 premenopausal breast cancer patients was investigated in relation to their history of early use of oral contraceptives. The women were born in 1939 or later and diagnosed in the southern health care region of Sweden.... more
The survival of 193 premenopausal breast cancer patients was investigated in relation to their history of early use of oral contraceptives. The women were born in 1939 or later and diagnosed in the southern health care region of Sweden. Women, who had started their oral contraceptive use (OC-use) before 20 years of age had a significantly lower survival rate as compared with those who had never used OC and late users (p = 0.02 and = 0.04 respectively, generalized Wilcoxon test). For women who started OC-use between 20 to 25 years of age, a tendency for a shorter survival was seen in comparison with women who had never used OC (p = 0.18). For all patients simultaneously, the relative risk adjusted for age at diagnosis increased for earlier OC-start. When only stages II and III were considered in a stratified multivariate model, a significantly elevated risk was seen for early users of OC irrespective of age or of adjuvant treatment given. The estrogen and progesterone receptor concen...
Research Interests: Menopause, Sweden, Humans, Female, Risk factors, and 4 moreAnticancer, Prognosis, Age Factors, and Risk Factors
Research Interests:
The national Swedish cancer registry was used to analyse the age-specific time trends in breast cancer incidence in Sweden from 1970 to 1984. The analysis included both a calendar year and a birth cohort approach to estimate time trends... more
The national Swedish cancer registry was used to analyse the age-specific time trends in breast cancer incidence in Sweden from 1970 to 1984. The analysis included both a calendar year and a birth cohort approach to estimate time trends in disease occurrence. According to the birth cohort approach there was a statistically significant increase in the incidence with an average annual increase of the incidence of 3.2% (P = 0.0114), 3.4% (P = 0.0002) and 2.2% (P = 0.0264) in the age groups 25-29, 30-34 and 35-39, respectively. Possible causes of the observed increasing incidence are discussed.
Research Interests:
In southern Sweden, extensive oral contraceptive use (OC use) among young women was a reality during the 1960s, thus making our region especially suited for studies investigating the hypothesis that early OC use is associated with the... more
In southern Sweden, extensive oral contraceptive use (OC use) among young women was a reality during the 1960s, thus making our region especially suited for studies investigating the hypothesis that early OC use is associated with the development of premenopausal breast cancer after a possible latency time between the exposure and the disease. The results of this study revealed that the risk of developing premenopausal breast cancer in women, who during the 1960s used the pill as teenagers, is five times greater than nonusers. The risk for early users is further modified by the duration of use at an early age, implying a dose-response relationship. Later use of OCs is not associated with an increased risk for the disease. Women with breast cancer, who at an early age have used the pill, have larger breast tumors, lower estrogen receptor concentrations of their primary tumor, and a worse prognosis compared with later and nonusers with breast cancer. The incidence of breast cancer in ...
Research Interests: Physiology, Research Methodology, Cancer, Biology, Risk, and 32 moreTreatment, Membrane Proteins, Population Dynamics, Histology, Health, Public Health, Adolescent, Medicine, Sweden, Safety, Side Effects, Interviews, Population, Humans, Prolactin, Measurement, Female, Hormones, Data Collection, Incidence, Risk factors, Hormone receptors, Middle Aged, Developed Countries, Adult, Public health systems and services research, Survival Rate, The Endocrine System Function, Prognosis, Age Factors, Risk Factors, and Case Control Studies
Research Interests:
The interaction between estradiol and its receptor in human endometrial adenocarcinoma was investigated in a human tumor-nude mice model. Estradiol treatment was found to activate estrogen receptor (ER), estimated through the measurement... more
The interaction between estradiol and its receptor in human endometrial adenocarcinoma was investigated in a human tumor-nude mice model. Estradiol treatment was found to activate estrogen receptor (ER), estimated through the measurement of ER in the nuclear fraction. The receptor activation in the tumors was significantly higher in tumors previously treated with estradiol than in previously non-treated tumors. The activation seems also to be dependent on the estrogen dose. We concluded, that previous influence of estradiol may change the sensitivity of estrogen receptor positive tumors for its hormone, and therefore the measurement of the receptor content alone does not seem to be a sufficient marker for the prediction of the receptor activation process.
Research Interests: Kinetics, Humans, Mice, Female, Animals, and 5 moreClinical Sciences, Cell nucleus, Estradiol, Adenocarcinoma, and Ovariectomy
Research Interests:
Research Interests:
The spermiograms of 63 fertile men (whose female partners were pregnant at the time of examination) were evaluated. A wide Gaussian distribution of the different semen parameters was found. Both parametric and nonparametric statistical... more
The spermiograms of 63 fertile men (whose female partners were pregnant at the time of examination) were evaluated. A wide Gaussian distribution of the different semen parameters was found. Both parametric and nonparametric statistical tests were applied and gave almost identical results. In a subgroup of 34 men, a second semen sample was analysed, but a significant difference (p less than or equal to 0.05) between the two samples was found only regarding the proportion of abnormal forms. Between various semen parameters significant correlations were found. There was no association between follicle stimulating hormone (FSH) and sperm density with sperm counts greater than 20 mill/ml.
Research Interests:
One hundred-eighty-five consecutive spermiograms from men of infertile couples in 1980-1981 were compared with as many spermiograms of age-matched controls from 1960-1961. The semen parameters analyzed were: volume, sperm density, and... more
One hundred-eighty-five consecutive spermiograms from men of infertile couples in 1980-1981 were compared with as many spermiograms of age-matched controls from 1960-1961. The semen parameters analyzed were: volume, sperm density, and sperm morphology. The following significant changes were noted over the time period: the mean seminal volume decreased from 3.79 ml to 3.42 ml (p less than 0.05), the mean sperm count decreased from 125.4 mill/ml to 78.0 mill/ml (p less than 0.001) and the proportion of double sperm heads increased from 0.52% to 1.51% (p less than 0.001). Further analysis showed even more pronounced changes in these parameters for men living in the urban area compared those from the surrounding rural areas.
Research Interests:
Research Interests:
ABSTRACT MEDOS is a case-control study where 9,000 persons were interviewed with an extensive questionnaire, either at time of fracture or in age-matched controls. Both men and women were studied. The MEDOS study has shown that several... more
ABSTRACT MEDOS is a case-control study where 9,000 persons were interviewed with an extensive questionnaire, either at time of fracture or in age-matched controls. Both men and women were studied. The MEDOS study has shown that several life-style factors were related with hip fractures, for example a low body mass index is associated with hip fractures and so was low calcium intake. Low physical exercise and immobilization were associated with a higher frequency of hip fractures. The attributable risk has been calculated so one can determine how many hip fractures a specific intervention could reduce, assuming a causal relationship.
Research Interests:
The Mediterranean Osteoporosis Study (MEDOS), a multicentre study on incidence, risk factors, and means of prevention of hip fracture in the Mediterranean region, started in 1986 and involved 14 centres, in Portugal, Spain, France, Italy,... more
The Mediterranean Osteoporosis Study (MEDOS), a multicentre study on incidence, risk factors, and means of prevention of hip fracture in the Mediterranean region, started in 1986 and involved 14 centres, in Portugal, Spain, France, Italy, Greece, and Turkey. The design includes a case-control study comparing 8,185 individuals in age groups above 50 (2,816 cases and 5,369 controls; two controls per case). Information on falls was only collected for a small fraction of the controls. In a questionnaire including 160 main questions eleven referred to circumstances around the fall. Falls were classified according to a) high risk environment, e.g. occurred in darkness and b) high risk fallers, e.g. confusion, reduced functional ability. There was great variation between centra for a majority of the results. However, 2/3 of fractures happened during daylight. 9% of fractures, same for both males and females, took place in darkness. Females have more indoor fractures than males. Around 15% of fractures took place in connection with going to the toilet. Mental factors play a minor role as reported immediate cause to the fall. Before the fall that caused the hip fracture between 28-84% could get up from a chair without any difficulties. Of the males 0-26% lived alone as against 0-37% or females. The data on circumstances around the fall shows a complex pattern with substantial variation between different cultures, but where a, however, minority took place under risk circumstances that have a clear preventive potential.
Research Interests:
In this study we investigated the importance of social network and social support systems outside the workplace and workload and psychological job strain in former work for the prevalence of daily neck and low back pain. The study... more
In this study we investigated the importance of social network and social support systems outside the workplace and workload and psychological job strain in former work for the prevalence of daily neck and low back pain. The study population (n = 621) comprised a random half of all male residents in Malmö, Sweden, born in 1914, of whom 500 (80.5%) participated. Two of the social network and social support indices (social anchorage and availability of material and informational support) were independent of life-style factors (leisure time physical activity, smoking and alcohol consumption) related to daily neck and back pain after retirement (OR = 2.0, 95% CI 1.2-3.4 and OR = 1.7, 95% CI 1.0-2.7, respectively), while the psycho-social and physical factors in former work were not. As no conclusion about the direction of the association can be drawn, prospective studies are needed to further explore these findings.
Research Interests: Pain, Life Style, Social Support, Low back pain, Sweden, and 15 moreHumans, Retirement, Public, Male, Interpersonal Relations, Aged, Prevalence, Questionnaires, Public health systems and services research, Odds ratio, Population Study, Neck, Cross Sectional Studies, Social Network, and Cohort Studies
Research Interests: Respiratory Medicine, Epidemiology, Sex, Carbon Dioxide, Treatment, and 19 moreAdolescent, Comparative Study, Sweden, Humans, Smoking, Female, Therapy, Male, Gender Difference, Clinical Sciences, Aged, Middle Aged, Oxygen, Adult, Vital Capacity, Sex Factors, Chronic obstructive pulmonary disease, Need, and Long Term
To describe and compare the pattern of antihypertensive drug prescriptions during different time periods. Antihypertensive prescriptions were registered in all patients who underwent an annual follow-up during 1998 (n = 984), 1992-1993 (n... more
To describe and compare the pattern of antihypertensive drug prescriptions during different time periods. Antihypertensive prescriptions were registered in all patients who underwent an annual follow-up during 1998 (n = 984), 1992-1993 (n = 924), and 1981 (n = 689), at the hypertension outpatient clinic in primary health care, Skara, Sweden. From 1981 to 1998 the total prescriptions of thiazides declined from 61 to 10% (p < 0.001), whilst prescriptions of calcium antagonists increased from 4 to 30% (p < 0.001), and ACE inhibitors from zero to 23% (p < 0.001). Prescriptions of calcium antagonists and ACE inhibitors increased during 1990-1995, but during 1996-1998 a significant decrease in primary prescriptions of calcium antagonists was demonstrated (OR: 0.15; 95% CI: 0.06-0.36). During all periods, females were more frequently treated with older types of antihypertensive drugs than males. In the analysis of total prescriptions in 1998 women were prescribed calcium antagonists (OR: 0.59; 95% CI: 0.45-0.78) and ACE inhibitors (OR: 0.43; 95% CI: 0.31-0.58) less frequently than men. There were significant changes in type of antihypertensive drugs used, both by time and between genders. Changes during the latest years indicate that the prescription pattern can be greatly influenced by new scientific reports and economic debate.
Research Interests: Primary Health Care, Comparative Study, Sweden, Humans, Hypertension, and 11 moreDiabetes mellitus, Diuretics, Female, Male, Support, Aged, Public health systems and services research, Drug Safety, Angiotensin Converting Enzyme Inhibitors, Pharmacoepidemiology and drug safety, and Calcium Channel Blockers
The aim of the present study was to elucidate the relations between demographic and socioeconomic factors, morbidity and the utilization of major drug groups in an urban Swedish population. The study was performed as an ecological... more
The aim of the present study was to elucidate the relations between demographic and socioeconomic factors, morbidity and the utilization of major drug groups in an urban Swedish population. The study was performed as an ecological analysis during November 1991 in the 17 different districts of Malmö, the third largest Swedish city (235,000 inhabitants). The material comprised 86,228 ACT-coded drug items which corresponded to 76% of all prescriptions dispensed during the study month. Of these, 43,032, dispensed to patients aged 15-64 years, were analysed in the present work. Age standardized drug utilization was expressed as the number of dispensed Defined Daily Doses per 1000 inhabitants per day. Morbidity was measured in terms of reimbursed days on sick leave. The sociodemographic parameters used were socioeconomic status (SES), employment rate, median income per family, households on social allowance, and ethnicity. For four of the five major pharmacological groups (ATC-groups A, C, J, N and R, i.e. alimentation, circulation, infectious diseases, nervous system and respiration), most pronouncedly group N and least so group R, utilization correlated positively with not only the extent of morbidity but also with an unfavourable socioeconomic situation, high proportion of immigrants, and households on social allowance or with low income and/or with a low employment rate. The utilization of antibiotics (group J), however, instead correlated negatively with these parameters. For all five drug groups, these trends were similar among men and women, albeit with varying strength. In conclusion, socioeconomic factors may have a profound influence on the utilization of several major drug groups. At least in the case of antibiotics, the consequence of this influence is irrational drug use.
Research Interests:
The role of vitamin D in the prevention of hip fracture is controversial and protective effects appear to be confined to the institutionalized and elderly population. The aim of this study was to assess the interaction of age and body... more
The role of vitamin D in the prevention of hip fracture is controversial and protective effects appear to be confined to the institutionalized and elderly population. The aim of this study was to assess the interaction of age and body mass index (BMI) on the effects of vitamin D on the risk of hip fracture in the community. We studied 1634 women with low-energy fractures of the hip aged 50 years or older, and 3532 age-matched controls from 14 centres in six Mediterranean countries (the MEDOS study), with a structured retrospective questionnaire. The use of vitamin D supplements was associated with a modest and non-significant decrease in the risk of hip fracture (RR = 0.74; 95% confidence interval (CI) 0.53-1.03; p = 0.07). The risk reduction was influenced by age and body mass. Women aged above 80 years had a significant decrease in the relative risk of hip fracture (RR = 0.63; 95% CI 0.40-0.98) as did women with a BMI below 20 kg/m2 (RR = 0.45; 95% CI 0.24-0.84). Elderly women were more likely to have a low BMI but the elderly did not appear to benefit from vitamin D where their BMI was 20 kg/m2 or higher. The findings could not be explained by differences in sun exposure or in physical exercise. We conclude that the use of vitamin D for the prevention of hip fracture might usefully be targeted to the frail and elderly.
Research Interests: Fracture, Vitamin D, Prevention, Osteoporosis, Humans, and 24 moreFemale, Low Energy Buildngs, Body Mass Index, Risk factors, Hip Fractures, Clinical Sciences, Association, Aged, Middle Aged, Risk Factor, Body mass index (BMI), Body Mass, Risk Reduction, Hip fracture, Retrospective Studies, Age Factors, Risk Factors, Physical Exercise, Elderly Women, Sunlight, Sunshine, Confidence Interval, Case Control Studies, and Relative Risk
Without Abstract
Research Interests:
Research Interests:
Research Interests:
In southern Sweden during the 1960s, women began to use oral contraceptives (OCs) extensively at a young age. This case-control study investigates the relationship between the use of OCs and breast cancer development in women in southern... more
In southern Sweden during the 1960s, women began to use oral contraceptives (OCs) extensively at a young age. This case-control study investigates the relationship between the use of OCs and breast cancer development in women in southern Sweden diagnosed in the early 1980s. The risk for breast cancer after OC use among premenopausal women was modeled, after adjustment was made for age, age at menarche, and age at first full-term pregnancy or parity. Both the duration of OC use before 25 years of age and commencement of OC use at a young age were associated with a significant increase in the risk of breast cancer as well as a significant trend. The duration of OC use before the first full-term pregnancy was associated with an increased risk of breast cancer, but it did not show a significant trend. The total duration of OC use was weakly, but not significantly, associated with breast cancer development. The odds ratio for women starting OC use before 20 years of age was 5.8 [95% confidence interval (CI), 2.6-12.8]; for women using OCs for greater than 5 years before age 25, it was 5.3 (95% CI, 2.1-13.2); and for women using OCs for greater than or equal to 8 years before first full-term pregnancy, it was 2.0 (95% CI, 0.8-4.7). In multivariate analyses including the different measurements of OC use, only starting age of OC use was significantly associated with breast cancer. The exposure-response relationship between duration of OC use and risk of breast cancer depended on the age at first use of OCs. Given a fixed duration of OC use, the risk increased with younger starting age of OC use. The findings point to the importance of the early reproductive years as risk determinants for breast cancer after OC use.