DISEASE CHARACTERISTICS: Hormone refractory metastatic prostate cancer (stage D1 or D2) with no greater than 3 prior endocrine manipulations PSA level increased on 3 consecutive measurements at least 2 weeks apart PSA at least 10 ng/mL (not required if measurable disease)

PATIENT CHARACTERISTICS: Age: Not specified Performance status: SWOG 0-2 Life expectancy: At least 12 weeks Hematopoietic: Granulocyte count at least 1,500/mm3 Hemoglobin at least 8 g/dL Platelet count at least 100,000/mm3 Hepatic: Bilirubin less than 2 mg/dL AST no greater than 2 times upper limit of normal Renal: Creatinine less than 2.0 mg/dL Other: No other serious medical illness No serious infection No other prior malignancy within the past 5 years except nonmelanoma skin cancer or any in situ carcinoma

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior chemotherapy Endocrine therapy: See Disease Characteristics Concurrent LHRH-agonist therapy allowed without antiandrogens At least 4 weeks since prior flutamide and nilutamide At least 6 weeks since prior bicalutamide At least 4 weeks since other prior hormone therapy including steroids Radiotherapy: At least 4 weeks since prior radiation therapy and recovered No prior strontium Surgery: Recovered from prior surgery