Colon polyp registries and colorectal cancer control.

This cohort of 252 subjects in the Roger Williams Hospital Polyp Registry who had adenomatous polyps removed in 1990, was followed for 6 years. Thirty subjects died during that period. Follow-up rate for the 222 living patients (88.1% of total) was 85%. New adenomatous polyps were found in 59% of the endoscoped subjects. Risk factors for new polyps included family history of colorectal carcinoma (p = 0.00079), right-sided location (p = 0.0108), and (probably) prior adenomatous polyps (p = 0.0595). In addition, three colorectal carcinomas, two of which were Dukes stage A, were found 1, 1, and 6 years after index polypectomy. If, as is common practice, the two first-year cancers are excluded, the observed incidence of metachronous colorectal cancer was 0.8/1000 patient years, which is substantially less than the expected incidence of such carcinomas in reference populations. Compared to the 1984 and 1987 cohorts in the polyp registry, colonoscopy was used more frequently and sigmoidoscopy less so for surveillance. Within the sigmoidoscopy group, the flexible instrument continued to rise in popularity as compared with rigid sigmoidoscopy. In addition to helping reduce the incidence of metachronous colorectal carcinomas, the polyp registry also serves the educational function of sensitizing physicians and their patients to the need to detect and treat these premalignant lesions. Enrollees in the registry also provide a source for studies designed to evaluate possible inhibitory effects of dietary, chemopreventive, and other agents on colorectal neoplasias.