Prostate-Specific Antigen Bounce after (125)I Brachytherapy Using Stranded Seeds with Intraoperative Optimization for Prostate Cancer

SIMPLE SUMMARY: Our study investigated clinical features of prostate-specific antigen (PSA) bounce in patients undergoing brachytherapy. PSA bounce is common and discriminating between large bounces and biochemical failures is very difficult. Therefore, we suggest important points to discriminate between large bounces and biochemical failures. In addition, we aimed to examine the clinical features and details of PSA bounce in patients receiving brachytherapy. ABSTRACT: Prostate-specific antigen (PSA) bounce is common in patients undergoing (125)I brachytherapy (BT), and our study investigated its clinical features. A total of 100 patients who underwent BT were analyzed. PSA bounce and large bounce were defined as an increase of ≥0.2 and ≥2.0 ng/mL above the initial PSA nadir, respectively, with a subsequent decline without treatment. Biochemical failure was defined using the Phoenix definition (nadir +2 ng/mL), except for a large bounce. With a median follow-up of 49 months, 45% and 7% of the patients experienced bounce and large bounce, respectively. The median time to bounce was 24 months, and the median PSA value at the bounce spike was 1.62 ng/mL, a median raise of 0.44 ng/mL compared to the pre-bounce nadir. The median time to bounce recovery was 4 months. The post-bounce nadir was obtained at a median of 36 months after low-dose-rate BT. On univariate analysis, age, the PSA nadir value at 2 years, and prostate volume were significant factors for PSA bounce. The PSA nadir value at 2 years remained significant in multivariate analysis. We should carefully monitor young patients with high prostate volume having a >0.5 PSA nadir value at 2 years for PSA bounce.