Combination Chemotherapy in Treating Patients With Advanced Colorectal Cancer

DISEASE CHARACTERISTICS: Histologically proven advanced adenocarcinoma of the colon or rectum No prior systemic chemotherapy OR Adjuvant chemotherapy only, completed 6 months prior to study and with subsequent development of recurrent disease At least 1 bidimensionally measurable lesion No CNS metastases PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: Greater than 12 weeks Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 2.0 mg/dL (no greater than 5.0 mg/dL if due to intrahepatic biliary obstruction not amenable to biliary decompression, if approved by the protocol investigator) SGOT no greater than 4 times upper limit of normal Renal: Creatinine no greater than 1.5 mg/dL Cardiovascular: No myocardial infarction within the past 6 months No congestive heart failure Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception No neurologic disease No active or uncontrolled infection No other malignancy within the past 5 years except nonmelanomatous skin cancer or carcinoma in situ of the cervix No medical or psychiatric disorders that would prevent compliance PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: See Disease Characteristics Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy for malignant disease Surgery: Recovered from any prior surgery Other: At least 30 days since other prior investigational agent No other concurrent investigational agents No concurrent anticancer agents