Background

Prostate cancer continues to be the most common lethal malignancy diagnosed in American men and the second leading cause of male cancer mortality. The American Cancer Society estimates that during 2005,∼ 232,090 new cases of prostate cancer will be diagnosed in the United States and 30,350 men will die of metastatic disease (1). Approximately 1 man in 5 will be diagnosed with prostate cancer during his lifetime, and 1 man in 33 will die of this disease. As the population ages, these numbers are expected to increase. Initially, almost all metastatic prostate cancers require testosterone for growth, and the role of androgen deprivation as a first-line therapy for metastatic prostate cancer has been recognized for more than 60 years (2, 3). Hormone deprivation is accomplished by surgical (orchiectomy) or medical (luteinizing hormone-releasing hormone agonists, antiandrogens) castration. Hormonal therapy leads to remissions lasting 2 to 3 years; however, virtually all patients progress to a clinically androgen-independent state resulting in death in∼ 16 to 18 months (4–9).