DISEASE CHARACTERISTICS: Histologically confirmed metastatic or locally recurrent adenocarcinoma of the colon or rectum Bidimensionally measurable disease Lesions seen on colonoscopic examination or barium studies, bone metastases, CNS lesions, CEA levels and ascites are not considered measurable No CNS disease only CNS metastases with other sites of measurable disease allowed provided appropriate therapy for CNS metastases has been administered and patient is neurologically stable and does not require intravenous steroid or anticonvulsant therapy