DISEASE CHARACTERISTICS: Histologically proven adenocarcinoma of the prostate Stage IV (D0.5; no evidence of disease on CT or bone scan after testicular androgen ablation) PSA progression after testicular androgen ablation with or without antiandrogen therapy Progression is defined as at least 2 consecutive rising PSA levels (drawn at least 2 weeks apart) with a greater than 50% rise above the last nadir level (arbitrary PSA at least 2 ng/dL)