Magnetic Resonance-guided Stereotactic Radiotherapy for Localized Prostate Cancer: Final Results on Patient-reported Outcomes of a Prospective Phase 2 Study

Background: The recent introduction of magnetic resonance-guided radiation therapy (MRgRT) has allowed improved treatment planning and delivery of stereotactic body radiotherapy (SBRT) in prostate cancer (PC). The health-related quality of life (HRQoL) outcomes using this novel approach are important in shared decision making for patients.

Objective: To report HRQoL using both patient- and clinician-reported outcomes at 1 yr following stereotactic MRgRT for patients with localized PC.

Design, setting, and participants: A prospective phase 2 trial included 101 patients with localized PC.

Intervention: All patients received 36.25Gy in five fractions of MRgRT delivered within 2 wk.

Outcome measurements and statistical analysis: HRQoL was prospectively assessed at baseline, at the last fraction, at 6 wk, and at 3, 6, 9, and 12 mo after treatment, by patient-reported outcome measures using European Organization for Research and Treatment of Cancer QLQ-C30 and QLQ-PR25 questionnaires, and International Prostate Symptom Score. At the same time points, clinicians reported on symptomatic adverse events (AEs). Effect sizes for changes in HRQoL were calculated with repeated measures analysis of variance.

Results and limitations: Availability of HRQoL data exceeded 95% at all study time points. From both questionnaires and the recorded AEs, the largest treatment effects on urinary and bowel symptoms were recorded in the first 6 wk of follow-up. Thereafter, all symptoms decreased and returned to baseline values at 12 mo. No grade ≥3 toxicity was reported. No patient reported any relevant limitation due to urinary symptoms, and only 2.2% of patients reported a relevant impact on daily activities due to bowel problems at 1 yr. The majority of patients had intermediate- or high-risk PC for which androgen deprivation therapy (83.2%) was prescribed, thereby precluding study of MRgRT on sexual function. Longer follow-up is awaited in order to evaluate the oncological outcome.

Conclusions: Delivery of MRgRT for SBRT resulted in low toxicity at 1 yr.

Patient summary: All patients completed magnetic resonance-guided radiation therapy, which was well tolerated with only transient early urinary and bowel symptoms, which resolved 1 yr after treatment, as confirmed by patient-reported outcome measures.