Treatment of bicalutamide-induced breast events

Bicalutamide is a competitive nonsteroidal androgen receptor antagonist. In the European Union and a number of other countries, bicalutamide 150 mg per day is approved as an adjuvant to primary treatments (radical prostatectomy or radiotherapy) or as monotherapy as an alternative to surgical or medical castration in men with locally advanced, nonmetastatic prostate cancer. The ongoing bicalutamide Early Prostate Cancer (EPC) program has shown that breast events, defined as gynecomastia, breast pain or both, are a significant limitation of bicalutamide. Nearly 90% of patients experienced one or both symptoms and nearly 16% of patients withdrew from the EPC program as a consequence of bicalutamide-induced breast events. Tamoxifen, anastrozole and radiotherapy have all been studied as options for the treatment of breast events. To date, tamoxifen appears to be the superior agent in terms of outcomes; however, further studies are still required to determine the optimal dose and timing of tamoxifen administration for both prophylaxis and treatment. In addition, the impact on prostate cancer control remains uncertain. An ongoing clinical trial using toremifene to prevent morphometric vertebral fractures in men undergoing medical and/or surgical castration will provide some additional data on the effects of selective estrogen receptor modulators in men with prostate cancer.