OUTLINE: This is a randomized, double blinded, placebo controlled, multicenter study. Patients are stratified according to quality of pain (mild vs moderate) and previous corticosteroids or one regimen of non-anthracycline-containing cytotoxic chemotherapy (e.g., estramustine) vs none. Patients are assigned to 1 of 2 treatment arms. Arm I consists of oral prednisone twice a day and intravenous mitoxantrone followed by intravenous clodronate administered over 3 hours every 3 weeks. Arm II consists of oral prednisone twice a day and intravenous mitoxantrone followed by intravenous placebo administered over 3 hours every 3 weeks. Doses are adjusted for myelosuppression. Treatment continues until disease progression (although patients initially on placebo can continue on open-label clodronate) or until the maximum cumulative dose of mitoxantrone is reached. Patients with a palliative response may continue on prednisone and the study drug (clodronate or placebo) until disease progression. Quality of life is assessed before and every 3 weeks during study treatment. A daily pain diary is also maintained. All patients are followed at 2 weeks and then every 3 months until death.