Histopathological documentation of prostate cancer confirmed in the NCI Laboratory of Pathology at the National Institutes of Health, the Pathology Department at Walter Reed Medical Center, or the Pathology Department at National Naval Medical Center, prior to starting this study. In addition, patients whose slides are lost or unavailable will be eligible for the study if they provide documentation of prostate cancer and if they meet criteria of clinically progressive prostate cancer as outlined (see below).