DISEASE CHARACTERISTICS: Histologically confirmed adenocarcinoma of the prostate Androgen independent disease progression -Castrate testosterone level of less than 40 ng/dL (if medically achieved, treatment must be maintained continuously) -Prostate specific antigen (PSA) at least 4 ng/mL and rising on at least 2 consecutive measurements No variant histologies such as ductal carcinoma (endometrioid or cribiform) or small cell carcinoma Brain metastases controlled