THE RISK OF ADENOMATOUS POLYPS IN ASYMPTOMATIC FIRST-DEGREE RELATIVESOF PERSONS WITH COLON-CANCER

Background & Aims: increasing evidence indicates that inherited suscep tibility is important in the pathogenesis of colorectal neoplasia. The aim of this study was to clarify whether having only one first-degree relative with colorectal cancer increases the risk of developing aden omatous polyps and whether total colonoscopy is an appropriate screeni ng measure in these patients. Methods: The frequency of such a history was evaluated in 397 asymptomatic patients who underwent total colono scopy. Of these patients, 155 had colorectal polyps and the remaining 242 did not have polyps. Results: Among polyp cases, 27 of 155 (17.4%) had a positive history; among those without polyps, 12 of 242 (5.0%) had a positive history. Alternatively expressed, 27 of 39 patients (69 %) with family history and 128 of 358 patients (36%) without family hi story had adenomas. The estimated risk for polyps associated with fami ly history was 1.9. Among polyp cases, 14 of 27 patients (51.9%) with family history and 32 of 128 patients (25.0%) without family history h ad only proximal polyps (chi(2) test; P = 0.006; odds ratio, 3.2). In the same groups, frequency of high-grade dysplasia was 8 of 27 patient s (29.6%) and 16 of 128 patients (12.5%), respectively (chi(2) test; P = 0.04; odds ratio, 2.9). Conclusions: Relative to subjects with no f amily history, asymptomatic patients with one first-degree relative wi th colorectal cancer had nearly double the risk of developing adenomat ous polyps, greater frequency of severely dysplastic lesions, and sign ificantly higher frequency of proximal polyp location. This suggests t hat total colonoscopy screening is indicated in these subjects.