Colorectal cancer is a malignant lesion of the gastrointestinal tract that seriously threatens human health and can cause great pain to patients, both in the disease itself and in the treatment. Therefore, although significant breakthroughs have been made in the treatment of colorectal cancer, we still need to do a good job in the prevention of colon cancer to prevent this disease from happening to us. Therefore, people who are in the environment with high incidence of colorectal cancer should have regular colorectal cancer screenings. In developed countries, colonoscopy is performed once a year for people over 50 years old, but 90% of them are patients over 40 years old. The risk of cancer increases with age, and most patients are diagnosed with the disease in their 50s and 60s. Risk factors include a history of breast, uterine or ovarian cancer, inflammatory bowel disease (ulcerative or clonal colitis), a family history of colorectal polyps or cancer. Most colorectal cancers develop from a single cell or group of cells in the intestine. These cells begin to differentiate and grow into non-cancerous (benign) bulky organisms called polyps. When these polyps get larger, they may become cancerous, infiltrating the intestinal wall or metastasizing to other parts of the body. Many colorectal polyps and tumors are asymptomatic until they become quite large, and it is important to detect a tumor when it is not yet large or active. Therefore, screening for people without symptoms will allow for early detection of these bulky growths or polyps. Even if you do not have risk factors present, you should have annual anal examinations and fecal occult blood tests starting at age 40. sigmoidoscopy of the lower intestine should be performed starting at age 50. If the physical examination is normal, it needs to be repeated every five years. People with general risk factors should be examined with a barium enema every 5 to 10 years or a colonoscopy every 10 years. People at high risk for colorectal cancer should have the entire colon and rectum examined. Colonoscopy is the best method, but sometimes a barium enema with a bendable sigmoidoscope is sufficient. Generally, a review is needed every 5 years. The timing of the first exam depends on risk factors. If there is more than one person in the family with colorectal cancer before age 50, screening should be started at age 40. If one parent has a familial multiple polyp, screening should begin at age 12 to 14. Those with a family history of colorectal cancer or polyps, or a personal history of colorectal cancer or adenomatous polyps, should have a colonoscopy. Any polyps should be removed and rechecked every 1 to 3 years. If the test is normal, a colonoscopy should be done once every 3 to 5 years. Women with breast, ovarian or uterine cancer should have a colonoscopy every 3 to 5 years starting at age 40. These are the people who are at risk of developing colon cancer, but it is not that these people will definitely develop this disease, but the prevalence of these people is higher than the general population. As long as you take appropriate preventive measures, there is nothing to worry about.