The diet of countries with high incidence of colorectal cancer is characterized by high fat, high animal protein, especially beef, and low crude fiber and refined carbohydrates, which is known as “Westernized diet”. The impact of high-fat diet (about 40% of total calories) is the most obvious. Nowadays, most of our children and teenagers like to eat western fast food, so they may have more chances to develop colorectal cancer in the future. Zhang Xinjun, Department of Gastroenterology, Affiliated Hospital of Ningbo University Medical College, also has a certain relationship with genetic factors on colorectal cancer. 30% of colorectal cancers have a genetic predisposition. There are more colorectal cancers inside the family, and there are more chances, especially in the immediate family. The increasing incidence of colorectal cancer in young people is caused by genetic mutations, and even genetic factors play a role. The main methods of colon cancer prevention are as follows: 1. Maintain a reasonable dietary structure Japan is a very good example of controlling the incidence of colorectal cancer. According to the survey, the amount of fat in the Japanese diet only accounts for 12% of the total calories, and the incidence of colorectal cancer is gradually decreasing. Easy-to-digest foods with high protein, high vitamin and low fat should be given and the intake of fatty foods should be reduced. Replace meat with too much animal oil with fish, poultry, lean meat and low-fat dairy products, and replace fried food with boiled and steamed food. Eat more fresh vegetables and fruits, especially yellow and green vegetables with high amounts of vitamin A and C. Eat more fiber-rich foods (cereal fiber or fruit and vegetable fiber), and do not eat an excessively fine diet; eat some coarse grains appropriately; consume less than 5 grams of salt per day. Reduce the intake of meat and fat, thus limiting the intake of saturated fatty acids; do not eat moldy foods; researchers at the University of North Carolina at Chapel Hill found that eating 18.3 grams of garlic per week (about six slices), whether raw or cooked, reduced the chance of stomach and colorectal cancer by 10 to 50 percent; the researchers said they did not find to The researchers said they did not find the efficacy of garlic supplements, but only the efficacy of natural garlic foods, the reason for which should not be clear. 2, maintain a good lifestyle Weight control and regular physical activity is the most conducive to the prevention of colorectal cancer; quit smoking, so as to prevent the absorption of carcinogenic substances in tobacco through the respiratory tract (tobacco contains dimethyl tibia, long-term smoking can induce colorectal cancer); limit alcohol, alcohol increases the risk of cancer by changing people’s dietary habits, such as low vitamin, low-folic acid diet; maintain good bowel habits Because of the prolonged stay of feces in the intestinal lumen, toxins in the feces (chemical carcinogens such as amines, phenols, ammonia, azo benzene, toxic products such as indole, methylindole, hydrogen sulfide, deoxycholic acid and stone bile acid, etc.) have a longer contact time with the intestinal mucosa, and cancer occurs in the intestinal wall under the stimulation of toxins over time. If there are changes in bowel habits, such as increased number of bowel movements, blood in stool, thin stools or sheep stool-like stools, and incomplete bowel movements, etc., timely consultation should be made to establish proper awareness of health care. (1) In Japan, Germany and the United States, legislation has been enacted to require citizens over 50 years old to receive annual colorectal cancer screening. (2) The high-risk groups of colorectal cancer are: those who are over 35 years old, rich and mainly eat meat; those who often eat barbecue food; those who drink coffee for a long time; those who work in a sedentary state for a long time; those who have long-term unprotected contact with asbestos, pesticides, herbicides, paints and many kinds of heavy metals; those who have a history of schistosomiasis; those who have confirmed colorectal adenoma, or those who have suffered from colorectal adenoma before: 80% of them are caused by colorectal cancer. More than 80% of colorectal cancers evolve from colorectal adenoma, which takes about 10 to 15 years. Once colorectal adenoma is found, it should be removed; however, more than 30% of patients will have new adenoma after removal of adenoma, so regular colonoscopy should be performed; about 2.5%-11% of colorectal cancer patients can have new colorectal cancer (heterochronous cancer) in the remaining colon after surgical removal, and the longer the time, the higher the incidence. Regular colonoscopy should be performed. Patients with frequent constipation; patients with so-called “bacillary dysentery” who are not cured by regular treatment; patients with no change in living environment but change in bowel habit; patients with change in stool appearance; patients with mucus or blood in stool or positive fecal occult blood test. People with family history of colorectal cancer (the risk is 2-4 times higher than that of the general population), especially if there are patients with colorectal cancer in the immediate family (80% of first-degree relatives will develop cancer), each member of the family should be examined regularly; patients with familial polyps; patients with ulcerative colitis (the risk is 6 times higher than that of the general population); Crohn’s disease; patients with gallbladder Patients with Crohn’s disease, gallbladder removal, and women with a history of lower abdominal radiation therapy should be vigilant and undergo colonoscopy once they have rectal symptoms such as blood in the stool, cramping, and changes in bowel habits. (3) What tests are needed for high-risk groups: Anorectal finger examination: Lower rectal cancer is far more common in China than abroad, accounting for 77.5% of rectal cancer, so most rectal cancers can be palpated during rectal finger examination. Fecal occult blood test: Although the fecal occult blood test is not specific for the diagnosis of this disease, it is a simple and easy method, and can be used as a screening tool for census, or can provide clues for early diagnosis. Routine blood test: observe whether there is anemia and the degree of anemia; Proctoscopy and sigmoidoscopy: 77.7% of colorectal cancers in China occur in the rectum and sigmoid colon, and the commonly used sigmoidoscope tube is 30cm long, which can directly detect tumors below the middle section of the anal canal, rectum and sigmoid colon. Barium enema: If the lesion is in the upper part of the sigmoid colon or higher, barium enema X-ray must be performed. Ordinary barium enema X-ray examination is easy to miss the diagnosis of small colorectal cancer, so it is better to use double air-barium imaging, which can improve the correct rate of radiological diagnosis and show the site and scope of cancer. Electronic colonoscopy: it can clearly observe the whole colon and can take suspicious lesions for pathological examination under direct vision, which is conducive to the detection of polyps, adenomas, early and microscopic colon cancer and the confirmation of cancer diagnosis, further improving the correct diagnosis rate of this disease, and is the most important examination means of colorectal cancer; due to the popularity of colonoscopy and the improvement of manipulation technology, it can be used as the preferred examination means. Serum carcinoembryonic antigen (CEA) measurement: carcinoembryonic antigen (CEA) can be detected in the serum of colorectal cancer patients. This is a glycoprotein, which is often found in the serum of patients with malignant tumors and is not a specific antigen for colorectal cancer, so serum CEA is not specific for the diagnosis of this disease. However, the detection of CEA by radioimmunoassay for quantitative and dynamic observation is meaningful for judging the surgical effect of colorectal cancer and monitoring the postoperative recurrence. If the tumor is completely removed by surgery, the serum CEA gradually decreases; if it recurs, it may increase again. Endorectal ultrasound scan can clearly show the scope, size, depth and surrounding tissues of rectal mass, and can distinguish the microstructure of each layer of rectal wall, which is a simple examination method and can provide images rapidly, which is helpful for choosing the operation mode and postoperative follow-up. CT examination: it is important to understand the degree of infiltration outside the intestinal canal of tumor and whether there are lymph nodes or liver metastasis, and it is more accurate for the diagnosis of rectal cancer recurrence.