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 highrisk status at RP and short time to BCR.