PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior immunotherapy Chemotherapy: At least 4 weeks since prior chemotherapy No concurrent chemotherapy Endocrine therapy: At least 4 weeks since prior flutamide or megestrol At least 6 weeks since prior longer-acting hormonal agents such as bicalutamide At least 4 weeks since prior hormonal therapy, except luteinizing hormone- releasing hormone agonist No concurrent hormonal therapy, including corticosteroids for cancer treatment Radiotherapy: No concurrent radiotherapy Surgery: See Disease Characteristics Other: No other concurrent investigational agents