Rectal cancer is cancer between the dentate line and the junction of the rectosigmoid colon, and is one of the most common malignant tumors of the gastrointestinal tract. The location of rectal cancer is low, so it can be easily diagnosed by rectal finger diagnosis and sigmoidoscopy. However, because of its location deep into the pelvic cavity and complex anatomical relationship, surgery is not easy to be complete and the recurrence rate after surgery is high. The proximity of lower and middle rectal cancer to the anal sphincter makes it difficult to preserve the anus and its function during surgery, which is a difficult problem in surgery and is also the most debated disease in terms of surgical methods. The median age of rectal cancer incidence in China is around 45 years old. The incidence rate of young people has a tendency to increase. 1.Anal finger examination can touch the lump: in addition to general symptoms such as loss of appetite, weight loss and anemia, patients with advanced rectal cancer also have symptoms of local irritation of cancer such as increased number of bowel movements, incomplete bowel movements, frequent bowel movements, and urgency and heaviness. 2.The enlargement of cancer may cause narrowing of intestinal cavity: signs of intestinal obstruction. If the cancer invades the surrounding tissues and organs, it may cause symptoms such as difficulty in urination, frequent urination and painful urination; if it invades the presacral plexus, it may cause pain in sacrococcygeal and lumbar region; if it metastasizes to the liver, it may cause hepatomegaly, ascites jaundice, and even cachexia. 3.The intestinal mucosa is stimulated to increase secretion: while a small amount of mucus secretion is discharged with stool. If the cancer continues to develop, the irritation of rectal mucosa will be greater, and the patient will feel mild discomfort in the rectum, or often have a sense of false stool, while mucus secretion will increase, and stripes of mucus are often seen on the surface of stool. Sometimes constipation may also occur, but it is not due to the narrowing of the intestinal lumen. Patients often have diarrhea and more mucus in the stool before the cancer tumor forms ulcers. When the surface of cancer tumor is ulcerated, the stool is thinner and can be watery and mixed with mucus and blood. 4.Invasion of surrounding tissues and organs by cancer: it may cause difficulty in urination, frequent urination, painful urination and other symptoms. 5.Invasion of presacral plexus: pain in sacrococcygeal and lumbar area; when metastasis to liver, it will cause hepatomegaly, ascites, jaundice, and even cachexia, etc. 6.Invasion of surrounding tissues and organs in late stage of rectal cancer: make patients have difficulty in urination, frequent urination and painful urination, etc. When rectal cancer invades the presacral plexus in late stage, it will cause pain in sacral tail and lumbar area. When rectal cancer metastasizes to liver in late stage, it will cause liver enlargement, ascites, jaundice, and even cachexia.