- The distal extent of the tumor must be >= 12 cm from the anal verge on endoscopy; if this distance was not confirmed on endoscopy pre-operatively, then the distal extent of the tumor must be >= 12 cm from the anal verge as determined by surgical examination; colonoscopy should be performed postoperatively for those unable to have a preoperative colonoscopy to guarantee there are no synchronous lesions; (if tumor is located beyond sigmoid colon and centimeter distance unavailable, include anatomic region of colon, e.g. right colon, transverse colon, hepatic flexure descending colon, cecum etc.)