Prostate-specific antigen bounce after permanent Iodine-125 implant brachytherapy in Japanese men : a nationwide J-POPS multi-institutional prospective cohort study

[Objective]: To evaluate the incidence of benign prostate-specific antigen (PSA) bounce and biochemical recurrence-free survival between PSA bounce and non-bounce patients treated with permanent prostate brachytherapy (BT). [Methods]: A total of 991 patients underwent BT without hormonal therapy or external beam radiotherapy. Three definitions of bounce were used: A, rise >35% over the previous value; B, rise >-0.2 ng/mL; and C, rise >-0.4 ng/mL, followed by a subsequent fall. [Results]: The likelihood of experiencing a PSA bounce was 46.5% for definition A, 42.9% for definition B, and 26.8% for definition C, with a median follow-up time of 60 months. Among the pre- and posttreatment factors, younger age predicted a PSA bounce on multivariate analysis using all definitions (A, P < 0.0001; B, P < 0.0001; C, P < 0.0001). The 5-year biochemical recurrence-free survival rate was 94.6%. Patients with a PSA bounce had better biochemical recurrence-free survival (98.1% with bounce vs. 91.7% without bounce, P < 0.0001 [definition A]). [Conclusion]: PSA bounce may possibly be a beneficial phenomenon following prostate BT and must be excluded before implementing salvage interventions.