Postoperative Radiation Therapy for Prostate Cancer: Comparison of Conventional Versus Hypofractionated Radiation Regimens

Purpose: To compare acute/late toxicity and biochemical control in contemporaneous prostate cancer patient cohorts treated with hypofractionated postprostatectomy radiation therapy (hypoPORT) or conventional PORT (coPORT). Methods and Materials: Consecutive patients treated with intensity modulated hypoPORT (2.5 Gy per fraction, median cumulative dose 65 Gy [range, 57.5-70 Gy]) or coPORT (1.8-2.0 Gy per fraction, median cumulative dose 66 Gy [range, 60-74 Gy]) between 2005 and 2016 at 2 institutions constituted the study cohort. Acute toxicity and cumulative late grade 2 and >= 3 genitourinary (GU) and gastrointestinal (GI) toxicity incidences were calculated for all patients using the Kaplan-Meier method and compared between cohorts. Biochemical progression-free survival (bPFS) was calculated in patients with >= 12 months' follow-up. Results: Median follow-up for all 461 patients was 38.6 months. Of the 461 patients, 167 (36%) received hypoPORT, and 294 (64%) patients received coPORT. The hypoPORT cohort had significantly worse baseline urinary incontinence. Acute grade >= 2 GU toxicity was more common after hypoPORT (22% vs 8%) (P=.0001). Late grade >= 3 GU toxicity cumulative incidence at 6 years was 11% (hypoPORT) and 4% (coPORT) (P=.0081). However, hypoPORT was not associated with late grade >= 2 GU toxicity on multivariate analysis (hazard ratio 1.39, 95% confidence interval 0.86-2.34) (P=.18). There was no difference in acute or late GI toxicity. In the subset of patients with >= 12 month's follow-up (n = 364, median follow-up 52 months), 4-year bPFS was 78% (95% CI 69.4-85.0) after hypoPORT (P=.0038) and 65% (95% CI 57.6-71.1) after coPORT. HypoPORT was not significant for bPFS on multivariate analysis (hazard ratio 0.64, 95% CI 0.41-1.02, P=.059). Conclusions: HypoPORT shows promising early biochemical control. After controlling for baseline urinary function, hypoPORT was not associated with greater GU toxicity than coPORT. (C) 2018 Elsevier Inc. All rights reserved.