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).

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.

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).

HypoPORT shows promising early biochemical control. After controlling for baseline urinary function, hypoPORT was not associated with greater GU toxicity than coPORT. © 2018 Elsevier Inc.