Long-term clinical outcomes after salvage radiotherapy in patients with biochemical recurrence after radical prostatectomy

Background This study aimed to evaluate the clinical outcomes of patients who developed prostate-specific antigen failure after radical prostatectomy and were treated with salvage radiotherapy (SRT). Methods This retrospective study included 167 patients who received SRT between January 2008 and August 2017 at a single center. Cumulative and periodic genitourinary and gastrointestinal adverse events and the chronologic changes in quality of life were evaluated before and 1, 3, 6, 12, 24, 36, 48, and 60 months after SRT. Results The median follow-up duration after SRT was 83 months. The 5- and 7-year biochemical recurrence-free rates were 52.6% and 47.9%, respectively. Multivariate analysis revealed the following independent risk factors for recurrence after SRT: higher total Gleason score (>= 8), higher pathological T stage, negative resection margin, and shorter period between radical prostatectomy and biochemical recurrence-free. The cumulative incidence rates of grade 2 or higher genitourinary and gastrointestinal adverse events after SRT were 27.4% and 9.4%, respectively. Bowel function worsened after SRT and showed significant deterioration 5 years after SRT, compared with pre-treatment. Five years post SRT, the rates of patients whose physical and mental component scores were < 50 were 44.1% and 34.3%, respectively. Conclusions Prostate-specific antigen recurrence occurred in approximately half of the patients after SRT, with a higher Gleason score, higher pathological T stage, negative resection margin, and shorter period between radical prostatectomy and first biochemical recurrence identified as risk factors. Besides the adverse events, careful attention to long-term quality-of-life deterioration must be considered when considering indications for SRT.