The incidence of colorectal cancer is on the rise globally, with an average annual increase of 2%, and the mortality rate in Europe and the United States ranks the 2nd in cancer deaths. Our survey shows that the average mortality rate of colorectal cancer is 4.54/100,000, ranking 5th in cancer deaths. The incidence of colon cancer in western countries is significantly higher than rectal cancer, but the characteristics of rectal cancer in China are: low value is the majority, low rectal cancer below the peritoneal fold is the majority, and the incidence site is adjacent to the anal sphincter; the incidence of rectal cancer in young people less than 30 years old is much more common than abroad. Therefore, the issue of whether to preserve the anus and the local recurrence after surgery has been a hot spot of research. An ideal radical rectal cancer surgery should be examined in terms of its biological characteristics, the law of recurrence and metastasis and the recovery of postoperative function, i.e., the postoperative survival period and the quality of survival should be examined in two aspects. Among them, adequate resection of primary tumor foci, reasonable lymph node clearance scope, and total resection of rectal mesentery are the principles that must be followed; selecting appropriate cases for functional extended radical surgery is the principle that should be followed as much as possible. Adequate resection of primary tumor foci The key to surgical treatment of rectal cancer is whether the anus can be preserved. An ideal anal preservation surgery should have minimal possibility of recurrence and good bowel movement control. To satisfy the former, sufficient bowel should be removed; to satisfy the latter, the integrity of the levator muscle should be maintained. On the contrary, disregarding these and only maintaining bowel continuity is never an ideal anal preservation surgery. Then, exactly how much of the normal intestinal canal should be removed below the lower edge of the tumor in order not to cause recurrence of the anastomosis after surgery? Studies have shown that the resection length of the distal anal canal of the tumor is an important factor affecting recurrence, as well as the existence of intramural reverse infiltration in rectal cancer. The fact that the distal anal canal of rectal cancer should be resected by 5 cm was considered one of the principles of anal preservation surgery in the last century. However, in recent years it is believed that although there is intramural retrograde infiltration, this phenomenon is uncommon, and when it does occur it is when the overlying lymphatic vessels are obstructed and rarely exceeds 3 cm. Studies have shown that only 50% of patients have retrograde infiltration, with an average infiltration distance of 2.2 cm and up to 4.4 cm in the most distal cases, and that retrograde infiltration is related to its pathological type, degree of differentiation and degree of peripheral infiltration. Therefore, resection of 3 cm distal intestinal canal is advocated, while special types such as hypofractionated adenocarcinoma and mucinous adenocarcinoma still need to reach 5 cm, and 2 cm can be resected in early cases. Some studies have shown that the recurrence of anastomosis after rectal cancer surgery is mostly caused by insufficient resection of the lower cut end. It is proposed that adequate resection of primary foci is the principle that must be followed. Once the anus-preserving surgery fails, then there is no more talk about the quality of survival. In addition, since rectal cancer is located in the narrow pelvic cavity, adjacent to prostate, bladder or uterus and vagina, it is easy to invade these organs once the tumor is too large and at a late stage of disease, it is necessary to choose combined resection as much as possible at this time to obtain good curative effect. Up to now, we have performed pelvic organ resection for 31 patients with rectal cancer infiltrating other organs, and the 5-year survival rate after surgery reached 43.3%. Reasonable lymph node dissection Lymphatic metastasis is one of the main ways for rectal cancer to spread. Japanese scholars in the 1920s, European and American scholars in the 1950s and Chinese scholars in the 1970s all clearly pointed out that there are extra-mural upward and downward lateral and triangular drainage pathways in the rectum, and pointed out that lateral is only the drainage pathway of the rectum below the peritoneal retrusion, and studies in the early 1980s showed that the rate of lateral metastasis is about 10%, mainly concentrated in the closed pore and internal iliac lymph nodes; lateral metastasis mainly occurs in the carcinoma below the peritoneal retrusion Lateral metastasis is related to many clinicopathological factors. The view that lateral clearance should be performed for tumors below the peritoneal regurgitation to avoid recurrence or metastasis due to residual lateral lymph nodes. And because of performing lateral lymph node dissection, it is easy to increase surgical comorbidities such as increased bleeding, ureteral injury, anterior sacral vein bleeding and pelvic vegetative nerve injury. For urinary and sexual dysfunction caused by physeal nerve injury, some improvement can be achieved by extended radical surgery with preservation of the pelvic physeal nerve. Our experience shows that extended radical surgery has some advantages in the treatment of rectal cancer and does not increase surgical complications, which is an ideal procedure to improve survival rate. However, even with extended lymph node dissection and adequate distal normal bowel resection, the local recurrence rate of rectal cancer is still high after surgery, which has aroused the concern of scholars. Professor Heald, a British scholar, first proposed total mesorectal resection in 1982, which was introduced to China in the early 1990s and is now one of the principles that must be followed in the surgical treatment of rectal cancer. This principle can be divided into three aspects: 1. sharp separation between the dirty layer and the wall layer of the anterior sacral fascia; 2. not to damage the anterior sacral fascia, especially emphasizing the importance of not damaging the dirty layer of the fascia; 3. the resection plane of the rectal mesentery should be 5 cm below the lower edge of the tumor. Preservation of pelvic vegetative nerve to reduce postoperative urinary and sexual dysfunction In recent 20 years, the incidence of postoperative urinary function and sexual dysfunction caused by pelvic vegetative nerve injury brought about by the expansion of surgery has also increased significantly, and expanded radical surgery to preserve pelvic vegetative nerve has been carried out at home and abroad.