Anatomical distribution of colonic carcinomas. Interracial differences in a community hospital population.

Three hundred ninety-five patients with colon cancer were identified from a community hospital tumor registry and the sites of their primary tumors determined. Two defined anatomical sites (right and sigmoid colons) and two regional anatomical areas (proximal colon including splenic flexure and distal colon) were used to tabulate the location of primary tumors. Patients were categorized into racial subgroups. Significant differences were found in the occurrence of primary tumors. Of all colonic cancers in whites, 50.9% developed in the sigmoid colon compared with 36.6% in blacks (P = 0.0047). Of all colonic cancers in blacks, 35.3% developed in the right colon vs 24.5% in whites (P = 0.02). Biological variables probably determine the differences. Black females and white males depicted age-incidence data that varied from expectations.