Gemcitabine and Irinotecan in Treating Patients With Locally Advanced or Metastatic Bladder Cancer

DISEASE CHARACTERISTICS: * Histologically confirmed transitional cell carcinoma of the bladder * Locally advanced or metastatic disease * Unidimensionally measurable disease by physical exam or imaging study * The following are not considered measurable disease: * Bone only disease * Pleural or peritoneal effusions * CNS lesions * Irradiated lesions unless disease progression was documented after radiotherapy * Not amenable to surgery PATIENT CHARACTERISTICS: Age * Over 18 Performance status * ECOG 0-2 Life expectancy * Not specified Hematopoietic * Granulocyte count ≥ 1,500/mm\^3 * Platelet count ≥ 100,000/mm\^3 Hepatic * Bilirubin ≤ 2.0 mg/dL Renal * Creatinine ≤ 2.0 mg/dL Gastrointestinal * No active inflammatory bowel disease * No significant bowel obstruction * No chronic diarrhea Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No other active malignancy except nonmelanoma skin cancer * No mental incapacitation or psychiatric illness that would preclude giving informed consent * No other severe disease that would preclude study participation PRIOR CONCURRENT THERAPY: Biologic therapy * No concurrent prophylactic filgrastim (G-CSF) or sargramostim (GM-CSF) Chemotherapy * No more than 1 prior platinum-based chemotherapy regimen * At least 4 weeks since prior chemotherapy * No prior irinotecan or gemcitabine * No other concurrent chemotherapy Endocrine therapy * No concurrent hormones except steroids for adrenal failure, hormones for non-disease-related conditions (e.g., insulin for diabetes), and intermittent dexamethasone as an antiemetic Radiotherapy * See Disease Characteristics * At least 4 weeks since prior radiotherapy * No concurrent palliative radiotherapy Surgery * Not specified Other * No concurrent participation in another clinical trial