Increasing incidence of right-sided lesions in colorectal cancer.

One hundred ninety-eight patients with 211 cancers of the colon and rectum underwent elective resection at the University of Vermont College of Medicine during the five year period 1971 through 1975. Analysis of this series demonstrated that 35 per cent of all cancers were located in the cecum and ascending colon, that a similar percentage were classified as Dukes' A cancers, that a synchronous cancer was present in 5.5 per cent of the patients and that diagnosis by rectal examination and sigmoidscopy was possible in only 32 per cent of the patients. Comparison of these results with published data during the past thirty years indicate that there is an increasing incidence of carcinoma of the right colon with an associated decrease in the incidence of carcinoma of the sigmoid colon and rectum. It is recommended that patients be screened by examination of the stool for occult blood rather than by rectal examination and sigmoidoscopy so that these proximal lesions can be diagnosed at an earlier stage. Preoperative evaluation of patients with distal colorectal cancer should include double contrast barium enema examinations and colonscopy to rule out synchronous right-sided lesions.