Elective pelvic versus prostate bed-only salvage radiotherapy following radical prostatectomy

Purpose To compare the impact of elective whole pelvic radiotherapy (WPRT) versus prostate bed-only radiotherapy (PBRT) on biochemical relapse-free survival (bRFS) in prostate cancer patients treated with salvage radiotherapy following radical prostatectomy (RP). Patients and methods In our database, 163 lymph node-negative prostate cancer patients who had undergone salvage radiotherapy (SRT) for biochemical relapse after RP between September 2004 and April 2012 were identified. PBRT was administered to 134 patients (the PBRT group), while the remaining 29 patients (the WPRT group) received WPRT. Results Median follow-up was 57 months (range 18122 months). In the propensity score-matched cohort, the 4-year bRFS of the WPRT group was significantly higher compared to the PBRT group (63.1 vs. 43.4 %, p = 0.034). Subgroup analysis showed that the bRFS of patients who had two or more risk factors (seminal vesicle invasion, Roach score for lymph node invasion >= 45 %, and number of harvested lymph nodes <= 5) and were treated with WPRT was significantly improved compared to those who received PBRT (hazard ratio, HR 0.33; 95 % confidence interval, CI 0.13-0.83; p = 0.018). Conclusion Elective WPRT for SRT may improve bRFS in patients with unfavorable risk factors. These results need to be confirmed by a prospective randomized trial.