OUTLINE: This is a randomized, double-blind, placebo-controlled, multicenter study. Patients are stratified according to disease progression (measurable or non-measurable disease progression vs prostate-specific antigen progression only), use of bisphosphonates at study entry (yes vs no), worst pain, measured by the Brief Pain Inventory "pain" scale (< grade 4 vs ≥ grade 4), and extraskeletal metastases (yes vs no). Patients are randomized to 1 of 2 treatment arms.