PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior growth factors No concurrent growth factors Chemotherapy: No prior systemic chemotherapy for bladder cancer No concurrent intravesical therapy At least 4 weeks since prior chemotherapy No concurrent chemotherapy Endocrine therapy: At least 4 weeks since prior high dose steroids or prednisone No concurrent high dose steroids No concurrent prednisone or its equivalent in excess of 10 mg/day Radiotherapy: No prior radiotherapy for bladder cancer At least 4 weeks since prior radiotherapy No concurrent radiotherapy Surgery: See Disease Characteristics Other: At least 4 weeks since prior carbamazepine or experimental drugs No concurrent carbamazepine or experimental drugs