Combination Chemotherapy in Treating Patients With Liver Metastases From Colorectal Cancer

DISEASE CHARACTERISTICS: * Unresectable liver metastases secondary to colorectal cancer * Less than 70% liver involvement on CT scan or MRI * Liver biopsy required before study unless 1 of the following conditions are met: * Carcinoembryonic antigen greater than 30 * 5 or more liver metastases visible on CT scan or MRI * Greater than 50% to under 70% liver involvement on CT scan or MRI * Histologically proven primary colorectal cancer that is resected or appears resectable on CT scan and physical exam * Documentation of previously resected primaries must be based on pathologic results of the resected tumor * Histological documentation of synchronous disease must be based on 1 of the following: * Biopsy of primary colorectal tumor before study * Suspicious lesion on barium enema, colonoscopy, or sigmoidoscopy, and a liver biopsy positive for adenocarcinoma consistent with the primary colorectal tumor * Measurable disease * Clearly defined liver mass measuring at least 2 cm or at least 3 liver masses on CT scan or MRI * No evidence of extrahepatic disease on CT scan and physical exam * No portal vein occlusion or ascites PATIENT CHARACTERISTICS: Age: * 18 and over Hepatic: * Bilirubin no greater than 2 times normal Other: * No other malignancy within the past 5 years except inactive nonmelanomatous skin cancer, carcinoma in situ of the cervix, or grade 1 bladder cancer * Not pregnant or nursing * Fertile patients must use effective contraception Chemotherapy: * At least 1 year since prior adjuvant chemotherapy comprising fluorouracil (5-FU) and leucovorin calcium (CF) or 5-FU, CF, and levamisole (LEV) * At least 6 months since prior adjuvant chemotherapy comprising 5-FU with or without LEV * No other prior chemotherapy * No other concurrent chemotherapy Endocrine therapy: * No concurrent hormonal therapy except for nondisease-related conditions, e.g.: * Steroids for adrenal failure * Insulin for diabetes * Intermittent dexamethasone as an antiemetic Radiotherapy: * No prior radiotherapy to the liver