Gemcitabine, Cisplatin, and Amifostine Following Surgery in Treating Patients With Locally Advanced Bladder Cancer

DISEASE CHARACTERISTICS: * Completely resected locally advanced bladder cancer * T2-4, N0-2 * Post radical cystectomy with no gross residual disease * No evidence of metastases by CT of chest, abdomen, and pelvis PATIENT CHARACTERISTICS: Age: * 18 and over Performance status: * Karnofsky 70-100 Life expectancy: * At least 12 weeks Hematopoietic: * WBC at least 3,500/mm\^3 * Platelet count at least 100,000/mm\^3 * Hemoglobin at least 9.0 g/dL (transfusion allowed) Hepatic: * Bilirubin no greater than 2 times upper limit of normal (ULN) * AST and ALT no greater than 3 times ULN Renal: * Creatinine no greater than 2.0 mg/dL OR * Creatinine clearance at least 50 mL/min Other: * Not pregnant or nursing * Fertile patients must use effective contraception during and for 3 months after study participation * No active infection * No serious concurrent systemic disorders that would preclude study participation * No metastatic cancer in past 5 years PRIOR CONCURRENT THERAPY: Biologic therapy: * No concurrent immunotherapy Chemotherapy: * No other concurrent chemotherapy Endocrine therapy: * No concurrent hormonal therapy except contraceptives and replacement steroids Radiotherapy: * No concurrent radiotherapy Surgery: * See Disease Characteristics * At least 4 but no more than 8 weeks since radical cystectomy Other: * No other concurrent experimental medications