PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior systemic biologic therapy for prostate cancer and recovered Chemotherapy: At least 4 weeks since prior chemotherapy (12 weeks for strontium-89 and 6 weeks for bicalutamide) and recovered Endocrine therapy: See Disease Characteristics Radiotherapy: See Disease Characteristics No concurrent radiotherapy Surgery: At least 3 weeks since prior major thoracic or abdominal surgery Other: At least 4 weeks since other prior investigational drugs (except bisphosphonates) and recovered