There is a male patient with rectal cancer, the tumor lesion is located at the edge of the anal canal, the tumor area occupies half of the intestinal canal, the colonoscopy directly reports the anal canal cancer, there is no report on the cell type of the tumor, there is no imaging report on the degree of infiltration, there is no intraoperative rapid freezing hospital conditions, the doctor in charge performed a radical rectal cancer surgery with preservation of the anus, the reason is that the family strongly requested to preserve the anus. The problem faced after such treatment is how to ensure that no tumor cells remain in the lower cut edge of the rectum? How to ensure that the preserved so-called anus can still function as an anus? If the postoperative pathology suggests high malignancy and vascular nerve invasion, how to do the next step of treatment? How to account for the local recurrence and metastasis faced in the next step with the preserved anus? With the development of laparoscopic techniques and the application of double anastomosis, the rate of preserved anus in rectal cancer has indeed increased significantly compared to a few years ago, and this increase is also due to the advancement of other aspects including preoperative staging pathological analysis techniques and the follow-up of adjuvant treatments such as radiotherapy! However, despite this, the probability of local recurrence of rectal cancer is still at a high level. The main reason for this is that patients and doctors are not fully aware of the concept that surgery is the first priority, and only thorough radical surgery can lay the foundation for postoperative adjuvant treatment, so that they can respond to all changes without change, and even if the postoperative pathological analysis is highly malignant, they can still have a good idea and doctors can have a clear conscience. Making the decision to preserve the anus easily is a rash and irresponsible act, which will result in the patient paying the price of life. Looking at comparisons at home and abroad, surgery is a major reason why the 5-year survival rate for colorectal cancer in China is lower than the rates in Europe and the United States! Ask some doctors know what is the meaning of columnar resection surgery for rectal cancer? Why do we need to perform columnar resection surgery? Why do we need to perform such APR surgery nowadays when the technology of low level anal preservation is so well developed? In a word, the question of the extent of resection and the question of whether the cure can be ensured by all means! Up to now, there are still some doctors who think that the basis of whether to preserve anus or not is only the distance between the tumor and the anus. This is a sign of lazy unthinking. Whether the anus can be preserved is a very prudent and very important issue to be studied, which needs to be carefully accounted and explained in the preoperative discussion, and a careful analysis and explanation should be made to the patient or the patient’s representative according to the requirements of tort liability law. Often ultra-low preserving anal surgery shows the level of the attending surgeon, especially if there is a controversy, but I must follow some principles: Is the distance between the tumor and the incision margin sufficient? Usually a distance of 2 cm is needed, but some people use a distance of 1 cm, but there needs to be enough certainty. In the case of highly malignant mucinous adenocarcinoma, a distance of 5 cm is needed distally. Are the conditions for rapid intraoperative freezing available? It is important to ensure that the distal cut edge of the tumor is free of cancer cells! Should the circumferential cut margin of the tumor be adequate? How much anal function can be preserved? Consider preserving the anus under the premise of ensuring the patient’s life as much as possible. In between, the doctor’s conscience is also an important factor!