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