Combination Chemotherapy in Treating Patients With Advanced Solid Tumors

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed solid tumor for which no curative or effective therapy is available No symptomatic or uncontrolled brain or leptomeningeal metastases CT scan required if clinical suspicion of CNS metastases PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: Not specified Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than upper limit of normal (ULN) AST no greater than 1.5 times ULN No acute hepatitis Renal: Not specified Cardiovascular: No unstable cardiac disease No history of cardiac arrhythmia (treated or untreated) No new onset crescendo or rest angina (stable exertional angina allowed) Pulmonary: Not specified Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception at least 1 week prior to, during, and for at least 2 weeks after study No known hypersensitivity to fluorouracil-uracil or leucovorin calcium No grade 2 or greater nausea/vomiting or diarrhea No significant neurological or psychiatric condition, including psychotic disorders, dementia, or seizures No active serious infection or septicemia No severe gastrointestinal bleeding No other serious illness or significant medical condition that would preclude study No psychological, familial, or sociological condition that would preclude study PRIOR CONCURRENT THERAPY: Biologic therapy: No concurrent immunotherapy Chemotherapy: At least 3 weeks since prior chemotherapy (6 weeks for mitomycin or nitrosoureas) and recovered No more than 1 prior chemotherapy regimen Prior fluorouracil and taxanes allowed Prior parenteral etoposide allowed Endocrine therapy: No concurrent anti-cancer hormonal agents Radiotherapy: At least 3 weeks since prior radiotherapy and recovered Prior radiotherapy to brain metastases allowed if stable neurological status achieved within 4 weeks of treatment No concurrent radiotherapy except for palliation of bone or brain metastases or pathological fractures of known lytic disease Surgery: Not specified Other: At least 3 weeks since prior investigational drugs and recovered No other concurrent anticancer drugs No other concurrent investigational therapy No concurrent halogenated antiviral agents such as lodenosine, fialuridine, clevudine, emtricitabine, or sorivudine No concurrent antiarrhythmic medication