Surgery With or Without Radiofrequency Ablation Followed by Irinotecan in Treating Patients With Colorectal Cancer That is Metastatic to the Liver

DISEASE CHARACTERISTICS: Histologically confirmed primary colorectal adenocarcinoma Hepatic metastases that are considered completely resectable No more than 4 metastases by dual phase CT scan OR Hepatic metastases that are not completely resectable but are amenable to complete destruction with resection and radiofrequency ablation More than 4 metastases allowed if all disease can be resected or destroyed in situ with radiofrequency ablation No extrahepatic disease in any location No recurrent or second primary colorectal cancer by colonoscopy within the past year Received prior adjuvant chemotherapy with a fluorouracil-based regimen with the last dose at least 1 month prior to surgery No prior radiofrequency ablation with residual viable intrahepatic disease by CT scan No plans to be treated with radiofrequency ablation alone without surgical resection PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-1 Life expectancy: Not specified Hematopoietic: Absolute neutrophil count at least 1,500/mm^3 Platelet count at least 100,000/mm^3 Hepatic: Bilirubin no greater than 1.5 times upper limit of normal (ULN) AST and ALT no greater than 5 times ULN No Gilbert's disease or other known defect in hepatic conjugation or glucuronidation Renal: Creatinine no greater than 1.5 times ULN Cardiovascular: No myocardial infarction within the past 6 months No congestive heart failure requiring therapy Other: Not pregnant or nursing Fertile patients must use effective contraception during and for 30 days after study No other malignancy within the past 5 years except inactive non-melanoma skin cancer or carcinoma in situ of the cervix No active serious infection No other serious underlying medical condition or severe concurrent disease that would preclude study participation No dementia, significantly altered mental status, or psychiatric illness that would preclude study participation No known hypersensitivity to irinotecan No known infection with HIV or AIDS No uncontrolled diabetes mellitus No history of seizures No drug or alcohol abuse within the past year PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: See Disease Characteristics No prior irinotecan Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy to more than 30% of bone marrow No prior radiotherapy to the liver At least 3 months since prior radiotherapy to the pelvis or other areas Surgery: See Disease Characteristics No prior resection of hepatic metastases (wedge biopsy allowed) Other: No concurrent phenytoin, phenobarbital, or other antiepileptic medication No concurrent enrollment in other investigational drug trials