Objectives: Single-agent therapy with bicalutamide, a nonsteroidal antiandrogen, was compared with castration, either surgical or medical, in patients with untreated Stage D2 prostate cancer.
Methods: In an open, randomized, multicenter trial, patients were randomized to treatment with 50 mg bicalutamide (n = 243) once daily or to castration (n = 243), either orchiectomy or depot injection of goserelin acetate every 28 days. Primary efficacy endpoints were times to treatment failure and objective disease progression and survival. Assessments included review of measurable metastases, prostate dimensions, Eastern Cooperative Oncology Group performance status, pain, analgesic requirements, and quality of life responses.
Results: The median duration of therapy was 39 weeks for bicalutamide-treated patients and 42 weeks for castrated patients; treatment failure occurred in 53% and 42% and disease progression in 43% and 33%, respectively. Treatment effects favored castration for both endpoints (P < or = 0.002), with hazard ratios (bicalutamide:castration) of 1.54 (95% confidence interval [CI], 1.18 to 2.00) for time to treatment failure and 1.6 (95% CI, 1.19 to 2.15) for time to disease progression. From the 1-year survival analysis, the hazard ratio for probability of death was 1.29 (95% CI, 0.96 to 1.72). Thus far, with a median follow-up of 86 weeks, median survival has not been reached in either group. Changes from baseline in several quality of life variables were significantly different (P < or = 0.01) between treatment groups periodically from months 1 to 6, and all favored bicalutamide. Overall, the antiandrogen was well tolerated compared with castration; with bicalutamide, hot flushes occurred less often and breast tenderness and gynecomastia more often.
Conclusions: Although a dosage of 50 mg of bicalutamide once daily was not as effective as castration, the favorable quality of life outcomes and the low incidence of nonhormonal adverse events provide reasons to evaluate bicalutamide, as a single therapeutic agent, at higher doses.