Any factor that can cause people to have an increased chance of developing colorectal cancer can be called a high-risk factor. Understanding these high-risk factors helps us to determine our potential risk and to take active prevention to reduce the likelihood of developing colorectal cancer. Risk factors for colorectal cancer include: having a family member with colorectal cancer or polyps, especially first-degree relatives (parents, siblings, children); having an inherited colorectal cancer syndrome diagnosed by a physician, such as hereditary non-polyposis colorectal cancer (Lynch syndrome), or familial adenomatous polyposis (FAP), the individual’s risk of colorectal cancer is significantly increased, and genetic testing individuals with inflammatory bowel disease, such as Crohn’s disease or chronic ulcerative colitis; and individuals with obesity. According to the body mass index formula, weight (kg)/height (m)2 is considered obese if it is >27.8 for men and >27.3 for women; people who consume a lot of red meat (such as beef, lamb and pork) for a long time or prefer to eat meat cooked at high temperatures such as roast meat; people with type II diabetes; long-term smokers; long-term heavy drinkers; and people who have had gallbladder removal surgery. More than 2,000 years ago, the Yellow Emperor’s Classic of Internal Medicine put forward the medical view that “the top doctor treats the untreated disease, the middle doctor treats the desired disease, and the bottom doctor treats the existing disease”, reflecting the scientific idea that “prevention is better than cure”: the real doctor is not the one who is good at treating diseases, but the one who can prevent them. In 1981, the World Health Organization pointed out that one-third of cancers can be prevented, one-third of cancers can be cured, and one-third of cancers can be treated effectively to prolong life and improve the quality of life. It can be seen that the prevention and early intervention of tumor is very important. For colorectal cancer, preventive measures include lifestyle prevention and medical screening. 1. Lifestyle prevention: maintain a healthy weight; participate in regular physical exercise; eat a healthy diet with more fresh vegetables and fruits; avoid smoking; drink alcohol in moderation; 2. Medical screening, mainly including the following four cases: (1) For people without high risk factors for colorectal cancer, they can choose one of the following methods for screening starting from age 50. Screening is no longer recommended after the age of 85. (1) Perform fecal occult blood test once a year. A positive fecal occult blood test indicates a small amount of bleeding in the gastrointestinal tract and requires further colonoscopy to rule out colorectal cancer or polyps. Fecal occult blood test may not prevent colorectal cancer, but it can help in early detection and early diagnosis. ② CT simulated colonoscopy is performed every 5 years. This method is almost painless and non-invasive, as it reconstructs images after CT scan and simulates colonoscopy to understand the condition of the intestine. Further colonoscopy can be done if colorectal polyps are found. (3) Colonoscopy should be done every 10 years. (2) For those who are found to have adenomatous polyps in the colorectum, it is recommended to repeat colonoscopy every 3-5 years after endoscopic removal of polyps. (3) For people with family history of tumor, especially those with first-degree relatives (parents, siblings, children) who have had colorectal cancer under 60 years of age, it is recommended to start colonoscopy at the age of 40, once every 5 years. (4) For family members with definite hereditary colorectal cancer syndromes, medical screening should be done earlier and more frequently. Specifically: Family members with familial adenomatous polyposis should undergo genetic testing at age 10 to 12 years to clarify whether they carry the mutated APC gene. If unfortunately a carrier, almost 100% will develop colorectal cancer around 30-40 years of age. If genetic testing is not done, annual sigmoidoscopy should be performed to detect polyp growth in the intestine. Family members with Lynch syndrome should have a colonoscopy every 1-2 years, starting at age 20-25. Genetic testing is also recommended to find out if they carry mutated mismatch repair genes.