Prostate-specific antigen bounce after 125I-brachytherapy for prostate cancer is a favorable prognosticator in patients who are biochemical recurrence-free at 4 years and correlates with testosterone

Abstract

Abstract Background Because patients with prostate-specific antigen (PSA) bounce do not experience biochemical recurrence (BCR) until PSA bounce occurs, the period until PSA bounce ends can be considered the so-called lead-time bias. Therefore, we evaluated differences in BCR-free rate in prostate cancer patients who were BCR-free 4 years after 125I-brachytherapy alone. Furthermore, we evaluated predictors for PSA bounce and the correlation between testosterone and PSA bounce. Methods From 2004 to 2012, 256 patients with prostate adenocarcinoma underwent 125I-brachytherapy alone. PSA and testosterone levels were monitored prior to 125I-brachytherapy, at 1, 3, 6, 12, 18, 24, 30, 36, 42, 48, 54 and 60 months after 125I-brachytherapy and yearly after 5-year follow-up. PSA bounce was defined as ≥0.2 ng/ml increase above the interval PSA nadir, followed by a decrease to nadir or below. Results BCR-free rate in patients with PSA bounce (100% 7-year BCR-free rate) was significantly better (P < 0.044) than that in patients without PSA bounce (95.7% 7-year BCR-free rate) in patients who were BCR-free 4 years after 125I-brachytherapy alone (n = 223). Age was the only predictor (odds ratio: 0.93, 95% confidence interval: 0.88–0.98, P = 0.004) for PSA bounce (n = 177). The testosterone level at PSA bounce was significantly higher (P = 0.036) than that at nadir before PSA bounce (87 cases). Conclusions Patients with PSA bounce had good BCR-free rate even in patients who were BCR-free 4 years after 125I-brachytherapy alone. Testosterone levels were higher at PSA bounce; increased testosterone levels may be a cause of PSA bounce.