Prostate Specific Antigen Bounce Is Related to Overall Survival in Prostate Brachytherapy

Purpose To investigate the association between prostate specific antigen (PSA) bounce and disease outcome after prostate brachytherapy. Methods and Materials We analyzed 975 patients treated with 125 I implantation monotherapy between 1992 and 2006. All patients had tumor Stage ≤2c, Gleason score ≤7 prostate cancer, a minimum follow-up of 2 years with at least four PSA measurements, and no biochemical failure in the first 2 years. Median follow-up was 6 years. Bounce was defined as a PSA elevation of +0.2 ng/mL with subsequent decrease to previous nadir. We used the Phoenix +2 ng/mL definition for biochemical failure. Additional endpoints were disease-specific and overall survival. Multivariate Cox regression analysis was performed to adjust for potential confounding factors. Results Bounce occurred in 32% of patients, with a median time to bounce of 1.6 years. More than 90% of bounces took place in the first 3 years after treatment and had disappeared within 2 years of onset. Ten-year freedom from biochemical failure, disease-specific survival, and overall survival rates were, respectively, 90%, 99%, and 88% for the bounce group and 70%, 93%, and 82% for the no-bounce group. Only 1 patient (0.3%) died of prostate cancer in the bounce group, compared with 40 patients (6.1%) in the no-bounce group. Adjusted for confounding, a 70% biochemical failure risk reduction was observed for patients experiencing a bounce (hazard ratio 0.31; 95% confidence interval 0.20–0.48). Conclusions A PSA bounce after prostate brachytherapy is strongly related to better outcome in terms of biochemical failure, disease-specific survival, and overall survival.