The Effect of Salvage Radiation Therapy on Survival, Functional Outcomes, and Quality of Life in Men with Persistent Prostate-specific Antigen After Robot-Assisted Radical Prostatectomy: Which Patient Benefits More?

Purpose: The aim of this study was to evaluate the effect of salvage radiation therapy (sRT) on survival, functional outcomes, and quality of life in men with persistent prostate-specific antigen (PSA > 0.1 ng/mL) after a robot-assisted radical prostatectomy (RARP) and reveal subgroups that benefit more from sRT. Methods and Materials: Data of 3409 patients who underwent RARP was retrieved from a high-volume institute database, and 313 patients with persistent PSA were included in further analyses. Patients who received sRT and those who did not were compared after propensity score matching. Progression-free survival (PFS), metastasis-free survival (MFS), androgen deprivation therapy (ADT)-free, cancer-specific survival, and overall survival, as well as patient-reported outcomes were the endpoints. Multivariable Cox regression models were developed to reveal treatment effect sizes for the subgroups. Results: The overall persistent PSA rate was 9.2%, and the median follow-up time after RARP was 4.5 years (interquartile range, 2.7-7.9 years). The sRT was associated with improved PFS (hazard ratio [HR]: 0.29; P < .001), ADT-free survival (HR: 0.34; P < .001), MFS (HR: 0.39; P = .001), cancer-specific survival (HR: 0.34; P = .03), and overall survival (HR: 0.24; P = .001). Positive surgical margins (HR: 0.26; P < .001 for ADT-free survival), advanced pathological T stage (HR: 0.24; P <.001 for PFS) and positive lymph nodes (HR: 0.15; P =.001 for MFS), and lower Gleason score (HR: 0.15; P = .001 for PFS) were associated with marked survival benefits of sRT. Bowel symptoms were observed more frequently in patients who had sRT with or without ADT compared with patients with persistent PSA but no sRT (34.3% vs 19.2%; P =.01). Early sRT (<6 months after surgery) was associated with bothering incontinence (P < .001) and bowel symptoms (P =.03). Conclusions: Persistent PSA after a radical prostatectomy is still a common challenge in the robotic surgery era. sRT provides clear survival benefits for all endpoints, especially with unfavorable locoregional factors but a low Gleason score. (c) 2022 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.