Clinical significance of distal colon polyps for the prediction of an advanced proximal neoplasm: The KASID prospective multicenter study

Background/aims: The possibility of proximal lesion without distal polyps is a weak point of sigmoidoscopic colon cancer screening, but the clinical significance of distal findings for advanced proximal neoplasm (APN) is uncertain. The aim of this study was to assess the significance of a distal finding as a predictor of APN. Materials and methods: Asymptomatic patients ≥50 years old were enrolled from among patients who underwent polypectomy at 11 tertiary medical centers during the Korean Association for the Study of Intestinal Disease prospective study conducted between July 2003 and March 2004. Polyps located distal to the splenic flexure were defined as distal polyps. An advanced neoplasm was defined as a polyp of ≥10 mm in size, and/or with villous features, and/or with high-grade dysplasia, or invasive cancer. Age, gender, and distal polyp size, appearance, and histology were analyzed as risk factors of APN. The sensitivity and positive predictive value of distal polyps for APN were calculated. Results: Data from 826 patients were analyzed. Mean patient age was 60.1 years (range 50-86), and 71.3% were men. APN was found in 98 patients, and 45 (45.9%) patients had no distal polyps. Risk factors of APN were a male gender, distal polyp size, and an advanced distal neoplasm. Sensitivities of a distal polyp of ≥10 mm and of an advanced distal neoplasm for APN were both 38.8% with positive predictive values of 13.3 and 14.4%, respectively. Conclusions: Although distal colon findings were found to be helpful for predicting APN in asymptomatic patients aged ≥50 years, APN without distal polyps requires careful consideration.