DISEASE CHARACTERISTICS: Histologically confirmed metastatic adenocarcinoma of the prostate Failure of androgen ablation (orchiectomy or luteinizing hormone releasing hormone, flutamide) -Rise in PSA greater than 50% of nadir confirmed by 2 measurements 1 week apart -Appearance of new soft tissue lesions -Appearance of new lesions on bone scan Measurable or evaluable disease No symptomatic ascites, pleural effusions, or peripheral edema greater than trace No brain or leptomeningeal involvement