DISEASE CHARACTERISTICS: Histologically confirmed metastatic or recurrent adenocarcinoma of the colon or rectum that is incurable by surgery or radiation therapy A metastatic lesion in the liver or lung should be evaluated for definitive surgical treatment before being considered for this study Measurable disease required Elevated CEA, hepatomegaly ascites, pleural effusion, positive nuclear scan or bone scan, or poorly defined pelvic or abdominal mass are NOT considered measurable disease Must have measurable disease outside the radiation port or progression of disease within a previously radiated area Must be eligible for a biopsy of a malignant lesion No ascites that are detectable on physical exam No brain metastasis