Risk of advanced proximal neoplasms in asymptomatic adults according to the distal colorectal findings

Background and Methods: The clinical significance of a distal colorectal po lyp is uncertain. We determined the risk of advanced proximal neoplasia, de fined as a polyp with villous features, a polyp with high-grade dysplasia, or cancer, among persons with distal hyperplastic or neoplastic polyps as c ompared with the risk among persons with no distal polyps. We analyzed data from 1994 consecutive asymptomatic adults (age, 50 years or older) who und erwent colonoscopic screening for the first time between September 1995 and December 1998 as part of a program sponsored by an employer. The location and histologic features of all polyps were recorded. Colonoscopy to the lev el of the cecum was completed in 97.0 percent of the patients. Results: Sixty-one patients (3.1 percent) had advanced lesions in the dista l colon, including 5 with cancer, and 50 (2.5 percent) had advanced proxima l lesions, including 7 with cancer. Twenty-three patients with advanced pro ximal neoplasms (46 percent) had no distal polyps. The prevalence of advanc ed proximal neoplasia among patients with no distal polyps was 1.5 percent (23 cases among 1564 persons; 95 percent confidence interval, 0.9 to 2.1 pe rcent). Among patients with distal hyperplastic polyps, those with distal t ubular adenomas, and those with advanced distal polyps, the prevalence of a dvanced proximal neoplasia was 4.0 percent (8 cases among 201 patients), 7. 1 percent (12 cases among 168 patients), and 11.5 percent (7 cases among 61 patients), respectively. The relative risk of advanced proximal neoplasia, adjusted for age and sex, was 2.6 for patients with distal hyperplastic po lyps, 4.0 for those with distal tubular adenomas, and 6.7 for those with ad vanced distal polyps, as compared with patients who had no distal polyps. O lder age and male sex were associated with an increased risk of advanced pr oximal neoplasia (relative risk, 1.3 for every five years of age and 3.3 fo r male sex). Conclusions: Asymptomatic persons 50 years of age or older who have polyps in the distal colon are more likely to have advanced proximal neoplasia tha n are persons without distal polyps. However, if colonoscopic screening is performed only in persons with distal polyps, about half the cases of advan ced proximal neoplasia will not be detected. (N Engl J Med 2000;343:169-74. ) (C)2000, Massachusetts Medical Society.