[en] The Southwest Oncology Group conducted a pilot study in patients who had had total clinical resection of cancer of the colon and had a high risk of recurrence (Duke's C); the purpose of the study was to determine the toxic effects of intra-arterial chemotherapy combined with hepatic radiotherapy, in anticipation of their potential use in an adjuvant groupwide protocol. The treatment plan included intra-arterial chemotherapy with mitomycin (3 mg/m2) on Days 1, 4, 35, and 38 by slow intra-arterial push and 5-FU (1000 mg/m2) on Days 1-4 and 35-38 by continuous 96-hour infusion. Radiation therapy was begun on Day 8 of therapy and consisted of 1950 rads in 13 fractions over 2 1/2 weeks. Nineteen patients have been studied. Of 13 fully evaluable patients, two have relapsed in the liver. Eleven patients have developed significant, persistent liver enzyme elevations, and one patient has died from therapy-related liver failure. Combined radiotherapy and intra-arterial chemotherapy may result in significant chronic liver damage, and caution should be exercised in future adjuvant trials