If annual colonoscopies are performed and polyps found are treated in a timely manner, it is certain that the risk of developing cancer will be significantly reduced. However, colonoscopy is a relatively invasive test, so it is difficult to do it every year. For individuals without significant family history and high-risk factors, if they can repeat colonoscopy once every 5-7 years, the risk of colon cancer can be reduced to a great extent. We often say that colorectal cancer is a relatively preventable solid tumor. It is because some colorectal cancers have polyps that gradually change and eventually form invasive carcinoma, and this cancer process can take 5-10 years, so there is a long window period, during which if colonoscopy finds polyps or adenomas, even high-level intraepithelial neoplasia, timely removal can interrupt the cancer process. Why is it that annual colonoscopy can substantially reduce the risk of cancer, but not avoid it? This is because a very small percentage of colorectal cancers are hereditary carcinomas. For example, in patients with Lynch syndrome, the carcinogenesis may not have the polyp – adenoma – cancer process described above. It may be a direct carcinoma from colonic mucosal epithelial cells. Some patients say I had normal colonoscopy last year, how come I have colorectal cancer one year later. It is very likely that this is the problem. Therefore, for patients with Lynch syndrome or hereditary bowel cancer, even the annual review is not frequent enough and needs to be shortened to once every six months.