A multi-institutional analysis comparing adjuvant and salvage radiation therapy for high-risk prostate cancer patients with undetectable PSA after prostatectomy

Abstract

Background and purpose In men with adverse pathology at the time of radical prostatectomy (RP), the most appropriate timing to administer radiotherapy (RT) remains a subject for debate. To determine whether salvage radiotherapy (SRT) upon early prostate-specific antigen (PSA) relapse is equivalent to immediate adjuvant radiotherapy (ART) post RP. Material and methods 130 patients receiving ART and 89 receiving SRT were identified. All had an undetectable PSA after RP. Homogeneous subgroups were built based on the status (±) of lymphatic invasion (LVI) and surgical margins (SM), to allow a comparison of ART and SRT. Biochemical disease-free survival (bDFS) was calculated from the date of surgery and from the end of RT. The multivariate analysis was performed using the Cox Proportional hazard model. Results In the SM−/LVI− and SM+/LVI− groups, SRT was a significant predictor of a decreased bDFS from the date of surgery, while in the SM+/LVI+ group, there was a trend towards significance. From the end of RT, SRT was also a significant predictor of a decreased bDFS in three patient groups: SM−/LVI−, SM+/LVI− and SM+/LVI+. Gleason score >7 showed to be another factor on multivariate analysis associated with decreased bDFS in the SM−/LVI− group, from the date of surgery and end of RT. Preoperative PSA was a significant predictor in the SM−/LVI− group from the date of RP only. Conclusions Immediate ART post RP for patients with high risk features in the prostatectomy specimen significantly reduces bDFS after RP compared with early SRT upon PSA relapse.