LAUSR

Background Colorectal cancer (CRC) is the second leading cause of cancer death worldwide. Opportunistic colonoscopy may be beneficial in reducing the incidence of CRC by detecting its precursors. Aim To determine the risk of colorectal adenomas in a population who underwent opportunistic colonoscopy, and demonstrate the need for opportunistic colonoscopy. Methods A questionnaire was distributed to patients who underwent colonoscopy in the First Affiliated Hospital of Zhejiang Chinese Medical University from December 2021 to January 2022. The patients were divided into two groups, the opportunistic colonoscopy group who underwent a health examination including colonoscopy without intestinal symptoms due to other diseases, and the non-opportunistic group. The risk of adenomas and influence factors were analyzed. Results Patients who underwent opportunistic colonoscopy had a similar risk to the non-opportunistic group, in terms of overall polyps (40.8% vs. 40.5%, P = 0.919), adenomas (25.8% vs. 27.6%, P = 0.581), advanced adenomas (8.7% vs. 8.6%, P = 0.902) and CRC (0.6% vs. 1.2%, P = 0.473). Patients with colorectal polyps and adenomas in the opportunistic colonoscopy group were younger (P = 0.004). There was no difference in the detection rate of polyps between patients who underwent colonoscopy as part of a health examination and those who underwent colonoscopy for other reasons. In patients with intestinal symptoms, abnormal intestinal motility and changes in stool characteristics were frequent (P = 0.014). Conclusion The risk of overall colonic polyps, advanced adenomas in healthy people undergoing opportunistic colonoscopy no less than that in the patients with intestinal symptoms, positive FOBT, abnormal tumor markers, and who accepted re-colonoscopy after polypectomy. Our study indicates that more attention should be paid to the population without intestinal symptoms, especially smokers and those older than 40 years.