PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: Not specified Endocrine therapy: See Disease Characteristics Greater than 4 weeks since prior flutamide (6 weeks for bicalutamide or nilutamide) No prior aminoglutethimide or ketoconazole for prostate cancer Continuation of primary testicular androgen suppression (i.e., LHRH analog) required Radiotherapy: Not specified Surgery: Not specified Other: No concurrent terfenadine, astemizole, cisapride, or other medicines known to interact with ketoconazole