DISEASE CHARACTERISTICS: Histologically proven locoregionally recurrent or metastatic adenocarcinoma of the colon or rectum Histologic or cytologic proof of adenocarcinoma consistent with colorectal cancer in a solitary lesion if plasma carcinoembryonic antigen level is no greater than normal Metastases not limited to bone, pleural effusion, or ascites Surgically resectable metastases not eligible No symptomatic brain metastasis At least one bidimensionally measurable lesion measuring at least 20 mm in one diameter outside a previously irradiated area