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

Prostate-specific antigen (PSA) bounce is common in patients undergoing ¹²⁵I 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.