Rectal cancer (rectalcancer) is a common malignant tumor in the gastrointestinal tract second only to stomach and esophageal cancer incidence is the most common part of colorectal cancer (accounting for about 65%) the vast majority of genetic patients over 40 years of age 30 years of age or less account for about 15% of men more common male to female ratio of 2-3:1, rectal cancer is a lifestyle disease. Currently, it has jumped to the second place in the list of cancers, so diet and lifestyle, is the bane of cancer. Because of the similarity of causes and symptoms, rectal cancer is often mentioned together with colon cancer. The cause of rectal cancer is still not well understood, but most believe that it is related to food or genetics. In the last decade or so, studies from various sources have proven that acidic food intake is the culprit of cancer, and that cancer is representative of an acidic body. In terms of food, the intake of meat, protein and fat is much higher, there is a significant increase in the trend of colorectal, and there are many patients who suffer from rectal cancer in their thirties. 1, chronic inflammation of the rectum: chronic ulcerative colitis, chronic schistosomiasis granulomas, etc. are directly related to the occurrence of colorectal cancer. The longer the duration of the disease, the higher the possibility of colorectal cancer, and the incidence of colorectal cancer in patients with ulcerative colitis for more than 20 years is about 20-40%. 2, rectal adenoma carcinoma. 3, diet and carcinogenic substances: epidemiological studies show that the occurrence of colorectal cancer is significantly related to economic status and diet structure. The incidence rate is significantly higher in economically developed regions, geographic areas and groups with high proportion of animal fat and protein in the diet and low fiber content. The exact mechanism of the relationship between dietary structure and colorectal cancer is not fully understood. It is generally believed that it may be related to the metabolites of animal fats, bacterial decomposition products and the increased absorption of toxins in the intestine due to the slowing down of intestinal peristalsis in a low-fiber diet. 4, genetic factors: In addition to patients with familial polyposis or ulcerative colitis caused by malignant colorectal cancer, about 5-10% of patients with other colorectal cancer have a significant family history of tumors, collectively known as hereditary non-familial polyposis colorectal cancer (HereditaryNonpolyposisColorectalCancer, HNPCC) It is also known as Lynch syndrome. (1) Three or more family members have colorectal cancer, two or more of whom are from the same generation; (2) At least two close generations have developed the disease; and (3) At least one of them was diagnosed with colorectal cancer before the age of 50.