Salvage Radiation Therapy Improves Metastasis-free Survival for Clinically Aggressive and Indolent Prostate Cancer Recurrences After Radical Prostatectomy

Objectives: To describe 5- and 10-year rates of metastasis-free survival (MFS) stratified by Gleason score (GS) and prostate-specific antigen doubling time (PSADT) for patients receiving salvage radiation therapy (SRT) after biochemical recurrence (BR) postradical prostatectomy (RP). Methods: A total of 236 patients who underwent SRT without receiving concomitant androgen deprivation therapy at a single institution after BR post-RP were retrospectively reviewed. The Kaplan-Meier methods and log-rank analysis were used to determine the MFS rates. Results: Median follow-up post-SRT was 7.1 years. As of last follow-up, 59 men (25%) had developed metastasis. On univariate analysis, both GS and PSADT predicted MFS (P<0.001). Five- and 10-year rates of MFS were calculated for patients with GS 2 to 6, 7, and 8 to 10 and for patients with PSADT < 3, 3 to 9, 9 to 15, and >15 months, who received no additional salvage therapy until the development of metastases. The 5- and 10-year MFS for GS 8 to 10 were 62% and 50%, respectively, compared with 94% at both 5 and 10 years for GS 2 to 6. The 5- and 10-year MFS for PSADT < 3 months were 70% and 61%, respectively, compared with 100% and 90% at 5 and 10 years, respectively, for PSADT >15 months. Conclusions: After BR post-RP, SRT results in low 5- and 10-year rates of metastasis after initial BR. Importantly, a substantial proportion of patients with high-risk disease (GS 8 to 10 or PSADT < 3 mo) are free from metastasis at these same time points. Therefore, SRT should not be withheld from patients based solely on the presence of adverse disease risk factors.