PRIOR CONCURRENT THERAPY: Biologic therapy: No concurrent filgrastim or sargramostim except for febrile neutropenia Chemotherapy: No other concurrent chemotherapy Endocrine therapy: No prior neoadjuvant or adjuvant hormonal therapy for prostate cancer No concurrent hormonal therapy except for non-disease related conditions (e.g., insulin for diabetes) No concurrent systemic corticosteriods unless for adrenal insufficiency No concurrent prednisone, dexamethasone, or other steroidal antiemetics At least 6 months since prior finasteride No concurrent finasteride No concurrent antiandrogens (e.g., flutamide, bicalutamide, nilutamide) or gonadotropin releasing hormone agonists (e.g., leuprolide, goserelin) Radiotherapy: No prior adjuvant radiotherapy for prostate cancer No prior pelvic radiotherapy for prostate cancer Surgery: See Disease Characteristics Other: At least 6 months since prior saw palmetto No concurrent compounds with 5 alpha-reductase inhibitor activity (e.g., saw palmetto)