Patterns of recurrence for advanced colon cancer modified by whole abdominal radiation and chemotherapy

Abdominal failure for colonic carcinoma patients following curative resection has been high in patients with advanced disease stage, particularly when increased numbers of lymph nodes are involved. Surgeons desire curative treatment for their patients, but they interpret local and regional lymph node recurrence as a failure of surgical resection. The effect of current adjuvant treatment protocols on modifying patterns of relapse, particularly in the abdomen, has not been well studied and is of interest to surgeons. We analyzed reported patterns of failure of patients with Stage C2 colon cancer from two colon cancer adjuvant treatment studies; 5-FU plus levamisole (SWOG 8591) and 5-FU, whole-abdominal radiation, and tumor boost. The total number of recurrences in SWOG 8591 at all sites was reduced. The percent of lung relapses was reduced from 34 per cent to 20 per cent in the treatment group, but the percentage of local relapse increased from 20 per cent in the observation group to 27 per cent in the 5-FU plus levamisole group. Similarly, the number of first relapses was fewer at a local site in the 5-FU plus levamisole group, but the percent of relapses at the local site was not reduced (18 vs. 22%). Advanced C2 patients who received regional treatment on 5FU and whole-abdominal radiation produced the lowest percent of local relapse (12%), suggesting a benefit for regional treatment. Further study of patterns of relapse after resection and adjuvant treatment in high risk C2 patients may lead to further progress in control of advanced, curative colon carcinoma.