Epidemiology of polyps in the rectum and sigmoid colon. Histological examination of resected polyps.

In an endoscopic screening study of rectosigmoidal polyps in a defined normal population aged 50-59 years, polyps 5 mm or larger in diameter were removed by diathermic snare resection for histological examination. Histological examination was possible in 50 of 55 polyps removed during colonoscopy from 27 men and 17 women. Of these polyps 41 (82%) were adenomas--12 with moderate dysplasia, 1 with severe dysplasia, and 2 with intramucosal carcinoma. In addition, a small ulcerating carcinoma, Dukes stage A, was found. A greater extent of dysplasia was found in rectosigmoidal adenomas in women, whereas more polyps were found in both distal and proximal parts of the colon among men. The size of adenomas and degree of dysplasia were unrelated to color of the lesions.