Rectal cancer is a common malignant tumor in the gastrointestinal tract second only to stomach and esophageal cancer in incidence is the most common part of colorectal cancer (accounting for about 65%) the vast majority of genetic patients over 40 years of age under 30 years of age 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 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, and there is a significant increase in the trend of colorectal, and there are many patients who get intestinal cancer in their thirties. 1, chronic inflammation of the rectum Chronic ulcerative colitis, chronic schistosomiasis granuloma, etc. are directly related to the occurrence of colorectal cancer. The longer the course 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%. 3.Diet and carcinogenic substances Epidemiological studies show that the occurrence of colorectal cancer is obviously related to economic status and diet structure. The incidence rate is significantly higher in economically developed areas, 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, and 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 intestinal tract due to the slowing down of intestinal peristalsis in the low-fiber diet. In addition to patients with familial polyposis or ulcerative colitis caused by malignant colorectal cancer, about 5-10% of other colorectal cancer patients have obvious family history of tumor, collectively known as Hereditary Nonpolyposis Colorectal Cancer (HNPCC), also known as Lynch syndrome. The specific manifestations are: (1) three or more family members have colorectal cancer, two or more of them are of the same generation; (2) at least two similar generations have developed the disease; (3) at least one of them was diagnosed with colorectal cancer before the age of 50. Clinical manifestations of rectal cancer 1. change in bowel habits, bloody stool, purulent stool, urgency, constipation, diarrhea, etc. 2. gradual thinning of stool, and in advanced stage, bowel obstruction, wasting and even malignant 3. rectal finger examination: it is a necessary examination step for the diagnosis of rectal cancer, and about 80% of rectal cancer patients can be diagnosed by natural rectal finger examination when they are graduated and found to have hard, bumpy masses; in advanced stage, narrowing of the intestinal cavity can be palpated 4.Proctoscopy: the size and shape of the tumor can be seen and the interventional tissues can be taken directly for pathological examination. 5.Obstruction symptoms are obstruction of the rectum by the cancer, with difficulty in defecation, less stool, abdominal pain and bloating. In some cases, intestinal pattern and hyperactive bowel sounds can be seen.