PATIENT CHARACTERISTICS: Age: Over 18 Performance status: ECOG 0-2 Life expectancy: Not specified Hematopoietic: Platelet count at least 100,000/mm3 Absolute neutrophil count at least 1,500/mm3 Hepatic: SGOT no greater than 1.5 times upper limit of normal (ULN) Bilirubin no greater than ULN No acute hepatitis Renal: Not specified Cardiovascular: No unstable cardiac disease requiring treatment No cardiac arrhythmia No new onset crescendo or rest angina Stable exertional angina allowed Neurological: No symptomatic peripheral neuropathy greater than grade 1 No significant neurological or psychiatric disorders including psychotic disorders, dementia, or seizures Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 2 weeks following study No other serious illness or medical condition No active infection, including septicemia No severe gastrointestinal bleeding No hypersensitivity to leucovorin calcium or fluorouracil-uracil No psychological, familial, sociological, or geographical condition that would preclude study