It may be that the patient’s tumor is in the rectum or in the sigmoid colon, or in the rectobasal junction. The tumor is usually found to be in the recto-basal junction during colonoscopy, as well as during an abdominopelvic enhancement CT scan. Tumors at the recto-B junction can be cleared by surgery for rectal cancer, usually by performing the Dixon procedure, which means that the patient is able to preserve the anus. If the surgery for rectal cancer, the tumor is low, generally within 5cm from the anal verge, it is very difficult to preserve the anus, and it is necessary to perform abdominal perineal colectomy, that is, to remove the tumor, and at the same time, it is also necessary to resect the anus of the perineum of the patient.