Colonic Polyp Study: Differences in Adenoma Characteristics Based on Colonoscopy History over 5-Year Follow-Up Period.

: Timely detection and removal of colonic adenomas are critical for preventing colorectal cancer. : This study analyzed differences in colonic adenoma characteristics based on colonoscopy history by reviewing the medical records of 14,029 patients who underwent colonoscopy between January and June 2020 across 40 primary medical institutions in Korea. : Adenoma and advanced neoplasia characteristics varied significantly with colonoscopy history ( < 0.05). In the first-time colonoscopy group, adenomas were more frequent in the sigmoid colon (S-colon) and rectum, with Is features and non-granular laterally spreading tumors. Advanced neoplasia was also more common in the S-colon and rectum, with Is and advanced-type features. In the <5-year group, adenomas were predominantly found in the transverse colon (T-colon) and descending colon (D-colon), with IIa and IIb features. Advanced neoplasia in this group was more frequent in the cecum and T-colon, with IIa and IIb features and laterally spreading tumors. In the ≥5-year group, adenomas were more commonly located in the ascending colon (A-colon) and cecum, with Ip features, while advanced neoplasia was more frequent in the A-colon and D-colon, also with Ip features. : Although every segment of the colorectum should be carefully observed regardless of colonoscopy history, these findings suggest that prioritizing specific colonic segments for examination based on colonoscopy history may improve adenoma detection rates and reduce the incidence of colorectal cancer. However, further large-scale, prospective studies are needed to confirm these findings and support their application in clinical practice.