S0306, Irinotecan in Treating Patients With Recurrent or Refractory Advanced Transitional Cell Cancer of the Urothelium Previously Treated With Chemotherapy

DISEASE CHARACTERISTICS: * Histologically confirmed transitional cell carcinoma (TCC) of the urothelium, including the bladder, renal pelvis, ureter, and urethra * Stage T2-4, N0-3, M1 OR stage T2-4, N+, M0, unresectable disease * The following additional histologic subtypes are eligible: * Poorly differentiated TCC * Predominant TCC with rare foci of squamous differentiation * Predominant TCC with rare foci of adenocarcinoma * The following histologic subtypes are ineligible: * Adenocarcinoma * Small cell carcinoma * Sarcoma * Squamous cell carcinoma * Mixed adeno/squamous/transitional histology * Incurable by surgery or radiotherapy * Progressed or recurred after 1, and only 1, prior cisplatin- or carboplatin-containing systemic regimen for metastatic disease * Measurable disease * Soft tissue disease that has been irradiated within the past 2 months is not considered measurable disease * No uncontrolled central nervous system (CNS) metastases * CNS metastases that have responded to or stabilized after prior radiotherapy are allowed PATIENT CHARACTERISTICS: Age * 18 and over Performance status * Zubrod 0-2 Life expectancy * Not specified Hematopoietic * Absolute granulocyte count at least 1,200/mm\^3 * Platelet count at least 100,000/mm\^3 Hepatic * Bilirubin less than 1.5 times upper limit of normal (ULN) * Aspartate aminotransferase (SGOT) less than 3 times ULN (5 times ULN if liver metastases are present) Renal * Creatinine less than 2 times ULN Other * Not pregnant or nursing * Fertile patients must use effective contraception * No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer, carcinoma in situ of the cervix, or adequately treated stage I or II cancer that is currently in complete remission PRIOR CONCURRENT THERAPY: Biologic therapy * Not specified Chemotherapy * See Disease Characteristics * At least 28 days since prior chemotherapy * No prior topoisomerase I inhibitors (e.g., irinotecan or topotecan) Endocrine therapy * Not specified Radiotherapy * See Disease Characteristics * At least 28 days since prior radiotherapy to the pelvis Surgery * Not specified Other * Recovered from prior therapy * Prior adjuvant therapy allowed * At least 14 days since prior Hypericum perforatum (St. John's Wort) * More than 7 days since prior phenytoin, phenobarbital, carbamazepine, or any other enzyme-inducing anticonvulsant drugs (EIACDs) * No St. John's Wort during and for 7 days after study participation * No concurrent EIACDs * No concurrent medications that cause myelosuppression * No concurrent medications that cause diarrhea * Concurrent gabapentin or other non-EIACDs are allowed