 This 4-year study will compare how safe and effective an oral investigational medicine is compared to placebo in preventing the development of prostate cancer in men that are defined by the study entrance criteria as being at an increased risk for prostate cancer. Study visits to the clinic will occur every 6 months for up to 4 years 10 clinic visits, and a prostate biopsy will be performed at 2 and 4 years of treatment. 