Hypofractionated versus conventionally fractionated radiation therapy for prostate carcinoma: Updated results of a phase III randomized trial

Purpose: The aim of this study was to compare the toxicity and efficacy of radiation therapy (RT) for localized carcinoma of the prostate, using a hypofractionated (55 Gy/20 fractions/4 weeks) vs. a conventionally fractionated (64 Gy/32 fractions/6.5 weeks) dose schedule. Methods and Materials: A total of 217 patients were randomized to either the hypofractionated (108 patients) or the conventional (109 patients) dose schedule, with planning with two-dimensional (2D) CT scan planning methodology in the majority of cases. All patients were followed for a median of 48 (6-108) months. Gastrointestinal (GI) and genitourinary (GU) toxicity was evaluated before RT and after its completion using modified late effects of normal tissue-subjective, objective, management, analytic (LENT-SOMA) scales and the European Organization for Research and Treatment of Cancer sexual function questionnaire. Efficacy of RT based on clinical, radiologic, and prostate-specific antigen data were also evaluated at baseline and after RT. Results: Gastrointestinal and GU toxicity persisted 5 years after RT and did not differ between the two dose schedules other than in regard to urgency of defecation. However, 1-month GI toxicity was not only worse in patients with the hypofractionated RT schedule but also adversely affected daily activities. Nadir prostate-specific antigen values occurred at a median of 18.0 (3.0-54.0) months after RT. A total of 76 biochemical relapses, with or without clinical relapses, have occurred since; of these, 37 were in the hypofractionated and 39 in the conventional schedule. The 5-year biochemical ± clinical relapse-free and overall survival was 55.9% and 85.3% respectively for all patients, and did not differ between the two schedules. Conclusions: Radiation therapy for prostate carcinoma causes persistent GI toxicity that is largely independent of the two dose schedules. The hypofractionated schedule is equivalent in efficacy to the conventional schedule