DISEASE CHARACTERISTICS: Histologically confirmed prostate cancer Disease progression with 3 or more rising PSA levels at least 2 weeks apart with greater than 50% rise above the baseline PSA, despite prostatectomy or radiotherapy Disease progression following primary therapy including surgery or radiotherapy with or without neoadjuvant androgen ablation allowed OR Intermittent hormonal therapy with noncastrate levels of testosterone (greater than 50 ng/mL) allowed No soft tissue and/or bone disease OR No androgen independence without evidence of radiographic disease No change in hormonal therapies (excluding therapies to maintain castrate testosterone levels) including prednisone or dexamethasone within 2 weeks of study No symptomatic or anticipatory (within 6 months) symptomatic disease No active CNS or epidural tumor No radiographic evidence of metastatic disease