DISEASE CHARACTERISTICS: Histologically diagnosed adenocarcinoma of the prostate Progressive metastatic or regional nodal disease after at least 4 weeks on flutamide, bicalutamide, or nilutamide, i.e.: Greater than 25% increase in sum of products of perpendicular diameters of all measurable lesions not previously irradiated OR Prostate-specific antigen (PSA) at least 5 ng/mL and risen from baseline on at least 2 successive occasions at least 2 weeks apart PSA progression required for "bone only" disease or disease that responded to androgen deprivation and is negative on imaging scans at entry Primary testicular androgen suppression with a luteinizing hormone-releasing hormone (LHRH) analogue plus antiandrogen or by orchiectomy required Intermittent LHRH analog/antiandrogen therapy resumed at least 4 weeks prior to and continued at time of entry LHRH analogue continued throughout study in absence of orchiectomy

PATIENT CHARACTERISTICS: Age: Any age Performance status: 0-2 Hematopoietic: Not specified Hepatic: Bilirubin no greater than 1.5 times normal AST no greater than 3 times normal Renal: Not specified Other: No active, uncontrolled condition including: Bacterial, viral, or fungal infection Hyperglycemia Gastric or duodenal ulcer No existing medical condition requiring systemic corticosteroids (inhaled and topical steroids allowed) No concurrent use of the following: Terfenadine Astemizole Cisapride

PRIOR CONCURRENT THERAPY: No prior therapy with experimental agents for metastatic disease Biologic therapy: No prior immunotherapy for metastatic disease Chemotherapy: No prior estramustine or other chemotherapy for metastatic disease Endocrine therapy: See Disease Characteristics No prior hormonal therapy for metastatic disease No prior aminoglutethimide No prior ketoconazole No prior hydrocortisone or other corticosteroids Prior experimental hormonal therapy requires approval of study chair Radiotherapy: At least 4 weeks since radiotherapy (8 weeks since strontium therapy) Surgery: Orchiectomy allowed