Postoperative local abdominal irradiation for cancer of the colon above the peritoneal reflection.

A retrospective analysis of 82 patients with cancer of the colon above the peritoneal reflection who received postoperative local abdominal irradiation was undertaken to assess the survival, patterns of failure, and toxicity of treatment. Forty-eight patients (adjuvant group) had a complete resection, but were felt to be at high risk for local relapse and received postoperative local abdominal irradiation. Thirty-four patients had gross residual disease following surgery. The 5-year actuarial survival and local relapse free survival were 67 and 67%, respectively, in the adjuvant group. In this group, local relapse was observed in 9 of 28 patients with Stage C disease in contrast to 3 of 20 patients with Stage B2 disease; 1 of 14 patients with lesions in the right colon failed locally compared to 11 of 35 patients with lesions in the left. Only 2 of the 34 patients with gross residual disease remained relapse free from 93% of patients having a component of local failure. The majority of the treatment morbidity was seen in patients with gross residual disease. Prospective randomized studies should be done to determine the efficacy of postoperative irradiation in patients with colon carcinoma who are at high risk for local recurrence following surgical resection.