Rectal cancer is a common malignant tumor, second only to gastric cancer among gastrointestinal malignant tumors, and most believe that the occurrence of rectal cancer is related to food or genetics. Rectal cancer develops between 30 and 60 years old, more men than women, and has a better prognosis if it can be detected early and treated timely. The cause of rectal cancer is not clear, and it is related to rectal polyps, chronic inflammation and genetic factors. According to the pathological changes can be divided into infiltrative, ulcerative and cauliflower type. Its metastatic routes are direct spread, lymphatic metastasis, hematogenous metastasis and peritoneal implantation. Currently, it has jumped to the second place in the list of cancers, so diet and lifestyle, are the bane of cancer. Because of the similarity of causes and symptoms, rectal cancer is usually mentioned together with colon cancer. Blood in the stool is one of the common symptoms of rectal cancer. Blood in stool is present in 50% of cases in the early stage of the disease, and the bleeding is small at the beginning, which is seen on the surface of stool, and becomes thick blood in stool after combined with infection. 2.In case of chronic intestinal obstruction, the abdomen is distended, with hyperactive bowel sounds and paroxysmal colic. 3.Systemic cachexia In the advanced stage of cancer, patients show loss of appetite, emaciation, weakness, anemia, jaundice, ascites, etc. Change of bowel habit, blood stool, pus stool, urgency, constipation, diarrhea, etc. Gradual thinning of stool, and in the advanced stage, there is obstruction of bowel movement, weight loss and even cachexia. Rectal finger examination: It is a necessary examination step for the diagnosis of rectal cancer. The tumor can be seen in size, shape and location, and the intervening tissues can be taken directly for pathological examination. The obstruction symptoms are obstruction of the rectum by the cancer, with difficulty in defecation, less stool, abdominal pain and bloating. In some cases, bowel pattern and hyperactive bowel sounds can be seen. Rectal cancer is a classification of colorectal cancer, and now the incidence of rectal cancer is increasing. Therefore, many people pay more attention to the late symptoms of rectal cancer, because many of them are in the middle and late stages of rectal cancer when they are discovered. However, even so, many people are still very vague about the late symptoms of rectal cancer and often consult with them. When the symptoms of rectal cancer are diagnosed to be advanced, the best time for treatment is already missed. Therefore, patients should pay more attention to the early symptoms of rectal cancer. In summary, the early symptoms of rectal cancer are: 1. change of normal bowel habit, constipation, diarrhea; 2. blood or mucus in stool; 3. recent persistent abdominal flatulence or hidden pain; 4. unexplained progressive anemia, emaciation, weakness; 5. palpable lumps in the department, etc.