Intramural spread of colon carcinoma. A pathologic study.

The results of a pathologic study of 42 colorectal cancers have been presented. Of the 42 lesions, only 2 demonstrated intramural spread. The maximum extent of intramural spread was 2 cm. In one case, intramural spread was in the distal direction. Thirty-six percent of the lesions were in the rectum or rectosigmoid, 19 percent were in the sigmoid colon, 19 percent were in the descending colon, 5 percent were in the transverse colon, and 21 percent were in the right side of the colon. Of the lesions, 14.2 percent were classified Dukes' A, 45.2 percent Dukes' B, and 35.7 percent Dukes' C. Two lesions showed widely disseminated disease. All were adenocarcinomas. Of the five low-lying Dukes' C lesions, three had positive distal lymph nodes. Based on a review of the literature and the findings of this study, a distal margin of resection of 2.5 cm is deemed acceptable. Patients with lesions clinically suspected to be Dukes' C, however, should undergo abdominoperineal resection in an attempt to eradicate distal intramural or lymphatic spread.