On October 12, 2014, the Department of Anorectal Surgery of our hospital completed the first technique in the region: a radical resection of rectal cancer with anal preservation was successfully performed for a patient with rectal cancer at a distance of 37.5px from the dentate line. Previously, a permanent colostomy (commonly known as anal diversion) was basically required for rectal cancer of such a distance. In this case, because the tumor did not break through the epithelium in the preoperative examination, and because the patient was younger (45 years old) and strongly requested to preserve the anus, we performed intersphincteric resection (ISR), a trans-sphincteric resection, to complete radical and anus-preserving surgery for ultra-low rectal cancer at The tumor was removed from the bottom up between the internal and external rectal sphincter 1 cm below the dentate line, and only the external anal sphincter, puborectalis muscle and part of the anal levator muscle were preserved, so as to ensure sufficient resection area to achieve the curative effect and preserve the anal function. The success of this surgery is a milestone in the region, and it announces the following information: First, in the future, anal preservation surgery for rectal cancer will no longer depend on how far the tumor is from the anus, but on the depth of tumor infiltration (there is no distance restriction for anal preservation surgery), and if the preoperative examination does not penetrate the muscle layer, the tumor can be removed radically and the anus can be preserved no matter how close to the anus. Secondly, it must be clarified that trans-sphincteric resection for ultra-low rectal cancer is not equivalent to the traditional pull-down surgery for rectal cancer, because trans-sphincteric resection for rectal cancer not only removes rectal cancer but also removes the internal anal sphincter, so as to ensure that the lower incision margin of the tumor is sufficient and can be cut all the way to the anal skin. As long as the tumor does not invade the rectal muscle layer, no matter how low it is, the tumor can be successfully removed and the anus can be preserved. Thirdly, without the aid of double anastomosis, the scope of resection is larger and the damage to the anal sphincter is smaller, which is more effective than double anastomosis for ultra-low rectal cancer and can save patients nearly 10,000 yuan in medical expenses. For surgeries that cannot be performed with double anastomosis, rectal cancer can still be cured and anus preserved by trans-sphincteric resection. Fourthly, since rectal cancer trans-sphincteric resection has cut to the anal skin, the colon is pulled down and anastomosed with the external anal sphincter, and the anastomosis is directly exposed, so there is no need to worry about peritonitis and intra-abdominal infection caused by anastomotic leakage. Fifthly, the abdominal operation is partially done by laparoscopy, and after the colon is pulled down and anastomosed, there is no incision in the abdomen, which is less traumatic and more beautiful, and in the future, we will vigorously promote this abdominal incisionless operation. To sum up, this surgery is of national advanced level. Trans-sphincteric interstitial resection can be used for anus-preserving surgical treatment of ultra-low rectal cancer with good radicality and better preservation of anal function. It is an optional radical anus-preserving method for patients with ultra-low rectal cancer, rectal mesenchymal tumor, basal extensive polyps and low rectal cancer with pelvic stenosis who are at an earlier stage or sensitive to preoperative radiotherapy or chemotherapy. Now the patient has fully recovered and the postoperative pathology returns: medium differentiated adenocarcinoma of the rectum (T2N0), no cancer is seen on both sides as well as on the peri-annular margin, and the surgical R0 resection has been achieved, and the patient is eating and defecating normally, and the anal function is good, with 2-3 bowel movements daily.