Proximal shift in the distribution of adenomatous polyps in Korea over the past ten years

Background/Aims: Several reports have suggested a trend of right-side shift of colorectal cancer; however, there were only a few studies on the chronologic changes in the distribution of adenomatous polyps. We aimed to study the changes in the distribution of colorectal adenomatous polyps over the past ten years. Methodology: We reviewed medical records of patients who underwent a colonoscopy at Yonsei University Severance Hospital, Seoul, Korea between January 1996 and December 2005. Patients who had an adenomatous polyp with a diameter of at least 5mm were included. Of these, patients with a history of colon resection, colorectal cancer, colorectal polyp, inflammatory bowel disease, HNPCC, or familial adenomatous polyposis were excluded. Results: A total of 2,498 patients and 4,591 adenomatous polyps were included in this study. Analysis with respect to number of patients showed significant increases in the proportion of patients with adenomatous polyp on the proximal colon, from 48.5% to 66.3% (p<0.001). Analysis with respect to number of polyps revealed that the proportion of adenomatous polyps on the proximal colon significantly increased from 48.9% to 62.3% (p<0.001). Conclusions: The proportion of adenomatous polyp on the proximal colon significantly increased over the past 10 years.