Rectal cancer is a cancer between the sigmoid-rectal junction and the dentate line, and is a common malignant tumor of the gastrointestinal tract, accounting for the second place of gastrointestinal cancer. Surgical resection is still the main treatment method for rectal cancer. Pre-operative radiotherapy and chemotherapy can improve the efficacy of surgery to a certain extent. Clinically, rectal cancer is classified into low (within 5cm from the dentate line), intermediate (5-10cm from the dentate line) and high rectal cancer (more than 10cm from the dentate line). This classification has an important reference value for the selection of radical surgery for rectal cancer. Surgical treatment: Any rectal cancer that can be resected without contraindications to surgery should be subjected to radical rectal cancer surgery as soon as possible. The scope of resection includes the cancer, sufficient intestinal segments, all or part of the adjacent organs invaded, surrounding tissues that may be infiltrated, and the whole rectal mesentery and lymph nodes. If radical surgery is not possible, palliative resection should be performed to relieve symptoms. If accompanied by resectable liver metastases should be removed at the same time. The choice of surgical method is based on the location, size, activity, degree of cell differentiation and preoperative bowel control ability of the cancer. Clinicopathological studies suggest that the extent of infiltration of rectal cancer into the distal intestinal wall is smaller than that of colon cancer. Less than 3% of rectal cancers infiltrate more than 2cm into the distal wall, which is an important basis for choosing the surgical method. Surgical methods: 1. Local excision: It is suitable for early rectal cancer with small tumor body, limited to mucosa or submucosa layer and high degree of differentiation. In principle, it is applicable to rectal cancer below the peritoneal fold, and the scope of resection includes the distal sigmoid colon, the entire rectum, the inferior mesenteric artery and its regional lymph nodes, the entire rectal mesentery, the anal levator muscle, the fat in the sciatic rectal fossa, the anal canal and 3-5 cm of skin around the anus, the subcutaneous tissue and the entire anal sphincter. A permanent single-lumen sigmoid stoma is performed in the left lower abdomen. In recent years, due to the use of gastrointestinal anastomosis, patients with rectal cancer who originally needed to make enterostomy were spared the pain of artificial anus and their quality of life was improved. 3.Transabdominal rectal cancer resection (low anterior rectal resection, Dixon surgery) 2.Radiation therapy: radiation therapy as an adjuvant therapy to surgical resection has the function of improving the efficacy. Pre-operative radiotherapy can improve the surgical resection rate and reduce the recurrence rate after surgery. Postoperative radiotherapy is only applicable to patients with advanced stage, patients whose surgery has not achieved radical cure or postoperative local recurrence. Chemotherapy: as adjuvant therapy to surgical treatment, it can improve the 5-year survival rate. The timing of chemotherapy, the combination of drugs and the dose vary from person to person, and individualized treatment is needed. Other treatments: gene therapy, guidance therapy, immunotherapy, etc. The efficacy is yet to be evaluated. Postoperative complications and prevention of rectal cancer: 1. Postoperative bleeding: exact intraoperative hemostasis. 2.Anastomotic leak: good anastomotic blood circulation, double-layer anastomosis, postoperative nutritional support. 3.Stoma stenosis: insist on postoperative anal dilation once a day. 4.Parastomal hernia: postoperative lap band with pressure bandage, avoid heavy physical labor, and release the factors of increased abdominal pressure. 5, postoperative defecation difficulties and sexual dysfunction: pay attention to protect the uninvaded pelvic nerve and genital nerve during surgery to avoid injury. 6, postoperative deep vein thrombosis: early activity and avoid prolonged bed rest. 7.Delayed or non-healing incision healing, incision liquefaction, infection, etc.: change medicine early after surgery, pay attention to observe the wound and deal with abnormalities in time.