Currently, the incidence of colorectal cancer is increasing in China, especially among middle-aged people over 50 years old. In the early stage, colorectal cancer usually has no obvious symptoms. When many patients are diagnosed, they are already in the middle or late stage, and the best time for treatment has been missed. Colonoscopy is very important for timely detection of colorectal cancer. Therefore, colonoscopy should be performed in both high-risk and general risk groups of colorectal cancer. How colonoscopy screening can prevent colon cancer. It is said that colorectal polyps are the “prelude” to colon cancer, and this is actually true. It is now clear that at least 80%-95% of colorectal cancers “evolve” from intestinal polyps step by step: small polyps → large polyps → severe atypical hyperplasia → carcinoma in situ → invasive cancer. Generally, this process may take 5-15 years (of course, there are a few cases with faster progress). Colorectal polyp is a bulging lesion on the surface of the intestinal mucosa, commonly known as a “meat lump” growing on the inner surface of the intestinal canal. If we have polyps in the intestine, we do not feel them and it is difficult to notice them subjectively. Some polyps are relatively safe, while others do not go away on their own, and if left untreated, they can grow slowly and have a higher chance of becoming cancerous. At this time, colonoscopy shows its great role, there is no sense of colon polyps in the colonoscopy nowhere to hide, can be removed immediately endoscopically. This operation is less invasive, has a shorter hospital stay, and can effectively cut off the path of polyp cancer. What is the situation in China? According to the 2015 China Cancer Statistics Report, the incidence of colorectal cancer in China is climbing year by year, but only less than 15% of people over 50 years old receive colonoscopy. So it seems that we still have a long way to go! Take action and mobilize the elderly over 50 years old around you to include colonoscopy in the list of medical checkups, stay away from cancer and cherish your health!