DISEASE CHARACTERISTICS: Histologically confirmed primary colorectal cancer Candidate for a clinically indicated laparotomy for primary tumor resection, resection of hepatic metastases, or placement of an intrahepatic arterial catheter No active CNS metastases defined by new or enlarging lesions on CT scan or within 3 months of treatment (i.e., surgery or radiotherapy) for brain metastases No prior participation in this study