Two years of bicalutamide monotherapy in patients with biochemical relapse after radical prostatectomy

Background: Salvage treatments for biochemical relapse (BCR) after radical prostatectomy (RP) have several problems in terms of indications or adverse events. We studied the possibility of 2 years of bicalutamide monotherapy for BCR after RP. Methods: Patients who showed BCR (prostate-specific antigen (PSA) ≥ 0.2 ng/ml) after RP were recruited. Protocol treatment was planned as 2 years of bicalutamide (80 mg/day) followed by observation. Protocol treatment failure was defined as PSA re-elevation of ≥0.2 ng/ml, clinical progression, any other treatments, or discontinuation or restart of bicalutamide. Primary endpoint of this study is time to protocol treatment failure from initiation of bicalutamide. Results: A total of 91 patients were registered between 2003 and 2009. Median age and PSA at initiating bicalutamide were 68 (range, 55-78) years and 0.32 (range, 0.19-7.91) ng/ml. Twenty-four (26.4%) patients could not complete 2 years of bicalutamide mainly due to progression of disease. Of the 91 patients, 2- and 5-year protocol treatment failure-free survivals were 74.6% and 33.0%, with a median follow-up of 76 (range, 11-118) months. Median time from initiating bicalutamide to treatment failure was 43 (95% confidence interval, 33-47) months. High-risk status at RP and time to BCR after RP < 6 months were significant predictors of second BCR. Conclusions: Two years of bicalutamide monotherapy should not be recommended as standard management for BCR after RP, but might be feasible for selected patients who do not have high-risk status at RP and short time to BCR.