Long-term results and predictive factors of three-dimensional conformal salvage radiotherapy for biochemical relapse after prostatectomy

PURPOSE: Salvage radiotherapy (RT) is used to treat patients with biochemical failure after radical prostatectomy (RP). Although retrospective series have demonstrated that salvage RT will result in biochemical response in approximately 75% of patients, long-term response is much lower (20-40%). The purpose of this study was to determine prognostic factors related to the prostate-specific antigen (PSA) outcome after salvage RT. METHODS AND MATERIALS: Between 1991 and 2004, 171 patients received salvage RT at the University of Heidelberg. Patient age, margin status, Gleason score, tumor grading, pathologic tumor stage, pre-RP and pre-RT PSA levels, and time from RP to rise of PSA were analyzed. RESULTS: Median follow-up time was 39 months. The 5-year overall and clinical relapse-free survival were 93.8% and 80.8%, respectively. After RT serum PSA decreased in 141 patients (82.5%). The 5-year biochemical relapse-free survival was 35.1%. Univariate analysis showed following statistically significant predictors of PSA recurrence after RT: preoperative PSA level (p = 0.035), pathologic tumor classification (p = 0.001), Gleason score (p < 0.001), tumor grading (p = 0.004), and pre-RT PSA level (p = 0.031). On multivariate analysis, only Gleason score (p = 0.047) and pre-RT PSA level (p = 0.049) were found to be independently predictive of PSA recurrence. CONCLUSIONS: This study represents one of the largest retrospective studies analyzing the outcome of patients treated with salvage RT at a single institution. Our findings suggest that patients with Gleason score <7 and low pre-RT PSA levels are the best candidates for salvage RT, whereas patients with high-grade lesions should be considered for additional treatment (e.g., hormonal therapy).