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