Many colon and rectal cancer patients have basically the same factors that cause the disease: frequent consumption of high fat, high animal protein, and little fiber, thus they are called cancers that come out of eating. In their prevention and treatment, doctors always emphasize eating more coarse fiber foods, such as sweet potatoes, leeks and cabbage, to stimulate intestinal peristalsis and help toxins to be excreted. However, patients with diagnosed bowel cancer must be finely processed when consuming coarse fiber foods. Some bowel cancer patients ask for coarse fiber food at meals, which can prevent constipation and diarrhea and ensure regular bowel movement every day, but they neglect the processing of coarse fiber food. However, the processing of coarse fiber food is neglected. If colon cancer bulges into the intestinal lumen and the intestinal lumen becomes narrow, dietary fiber intake should be controlled because excessive intake of dietary fiber will cause intestinal obstruction. At this time, easily digestible and soft semi-liquid food should be given, such as millet porridge, lotus root soup, cornmeal porridge, etc. These foods can smoothly pass through the intestinal lumen, reduce intestinal irritation and prevent intestinal obstruction from occurring. If the disease has progressed to advanced stage, it is more important to control the intake of coarse fiber food. Patients are advised to drink more honey water and eat more bananas and pears, among which honey has the best laxative effect. It takes 5 to 10 years to develop from precancerous lesions to invasive tumors. During this period, it is not only necessary to pay attention to diet, but also to receive regular colonoscopy and other related examinations. Colonoscopy is not as scary as imagined. During the examination, patients will be injected with sedatives to reduce pain, and the whole examination process only takes 15~30 minutes, and they can resume normal activities the next day. In addition, some patients mistakenly believe that only colonoscopy can be done for colorectal cancer diagnosis, but in fact, sigmoidoscopy, fecal occult blood test and colon gas-barium double imaging can also help in diagnosis, only that colonoscopy can detect more cancers and complete the examination, diagnosis and removal of polyps in one time, which is called the “gold standard”. Therefore, those who have blood in stool, abdominal pain, change in stool habit or constipation should undergo anorectal examination, and the examination cycle should be 3-5 years; those who have intestinal polyps closely related to intestinal cancer should be examined once every two years; for those who have family history of genetic predisposition, the screening age should be advanced to 45 years old.