Benjamin Spieler BA, Jeffrey Goldstein MD, Yaacov R. Lawrence MD, Akram Saad MD, Raanan Berger MD PhD, Jacob Ramon MD, Zohar Dotan MD, Menachem Laufer MD, Ilana Weiss MA, Lev Tzvang MS, Philip Poortmans MD PhD and Zvi Symon MD
Background: Radiotherapy to the prostate bed is used to eradicate residual microscopic disease following radical prostatectomy for prostate cancer. Recommendations are based on historical series.
Objectives: To determine outcomes and toxicity of contemporary salvage radiation therapy (SRT) to the prostate bed.
Methods: We reviewed a prospective ethics committee-approved database of 229 patients referred for SRT. Median pre-radiation prostate-specific antigen (PSA) was 0.5 ng/ml and median follow-up was 50.4 months (range 13.7–128). Treatment was planned and delivered using modern three-dimensional radiation techniques. Mean bioequivalent dose was 71 Gy (range 64–83 Gy). Progression was defined as two consecutive increases in PSA level > 0.2 ng/ml, metastases on follow-up imaging, commencement of anti-androgen treatment for any reason, or death from prostate cancer. Kaplan-Meier survival estimates and multivariate analysis was performed using STATA.
Results: Five year progression-free survival was 68% (95%CI 59.8–74.8%), and stratified by PSA was 87%, 70% and 47% for PSA < 0.3, 0.3–0.7, and > 0.7 ng/ml (P < 0.001). Metastasis-free survival was 92.5%, prostate cancer-specific survival 96.4%, and overall survival 94.9%. Low pre-radiation PSA value was the most important predictor of progression-free survival (HR 2.76, P < 0.001). Daily image guidance was associated with reduced risk of gastrointestinal and genitourinary toxicity (P < 0.005).
Conclusions: Contemporary SRT is associated with favorable outcomes. Early initiation of SRT at PSA < 0.3 ng/ml improves progression-free survival. Daily image guidance with online correction is associated with a decreased incidence of late toxicity.