Low rectal cancer: Sphincter preserving techniques-selection of patients, techniques and outcomes

Table 1 Table comparing the different surgical techniques, regarding their oncological outcomes, complication and success rate as well as the ideal patient selection criteria

	Patients selection(inclusion criteria)	Surgical technique	Postoperative outcome		Oncological outcome
ISR	T1-3 tumors within 30-35 mm from the anal verge	Abdominal phase: high ligation of the inferior mesenteric vessels	Morbidity:	8%-64%	Local recurrence	2.6%-9.5%
					Lymphnode metastases	2.40%
		Perineal phase: dissection on the anatomical plane between the IAS and the EAS	Mortality	0%-1.7%	Distant metastases	9.3%-14.1%
					CRM (-)	80.4%-96%
					5-yr overall survival	76.4%-86.3%
APPEAR	Was developed to treat patients with malignant or benign disease, needing APR or completion protectomy, if treated with conventional surgery	Abdominal phase, same as TME in LAR	Morbidity:	15.4%-60%	Distal resection margin	Median: 20 mm
	Mostly used in rectal cancer 2-5 cm from anal verge	Perineal phase involves a convex crescentic incision in the perineum, between vagina/scrotum and anus, the dissection continues upwards to the plane made from abdominal phase. The rectum is freed laterally and posteriorly from the perineal aspect and the specimen delivered through the perineum	Mortality	0%	CRM	Median: 5 mm
					Local recurrence	0%
TEM TAMIS	(1) Are indicated for: mobile/nonfixed tumors, less than 3 cm in size, occupying less than 1/3 of the circumference of the bowel, not extending beyond the submucosa well to moderately differ-rentiated with low-risk histopatho-logical features	Adenomas located within the intraperitoneal portion of the rectum: careful muco-sectomy, avoiding entry into the peritoneum	TEM Morbidity	6%-31%	Without neo-adjuvant CRT
				7.4%-19%
		Extraperitoneally located adenomas: full thickness resection	TAMIS Morbidity	Occasionally	T1sm1: Local recurrence	< 5%
		All invasive carcinomas: full thickness resection	TEM Mortality	Occasionally	T1sm2-3: Local recurrence	20%
	(2) As a palliation in patients with advanced rectal cancer who either refuse radical excision or they are poor surgical candidates	Circumferential adenomas in the lower and middle rectum: complete full thickness resection, followed by an end-to-end anastomosis	TAMIS Mortality		After neo-adjuvant CRT
	(3) Furthermore, TAMIS is used for the repair of rectoure-theral fistulae, distal rectal mobilization, extraction of rectal foreign bodies, and for transanal TME				T2N0:
					Local recurrence	5.7%
					Distant recurrence	2.8%
					Combined recurrence	9%
					After neo-adjuvant CRT
					T2-3N0 (ypT0):
					Local recurrence	0%
					Systematic recurrence	4%
					T2-3N0 (ypT1):
					Local recurrence	2%
					Systematic recurrence	7%
					T2-3N0 (ypT2):
					Local recurrence	7%
					Systematic recurrence	7%
					T2-3N0 (ypT3):
					Local recurrence	21%
					Systematic recurrence	12%
TaTME	Was developed to overcome technical difficulties associated with laparoscopic TME, mainly related to narrow pelvis, visceral obesity or large tumor diameter	Abdominal phase involves high ligation of inferior mesenteric vessels and mobiliazation of left colon and splenic flexure	Morbidity	22.7%-26%	Distal resection margin	Median: 10 mm
		Perineal phase:	Mortality	0	CRM	Median: 2 mm
		for tumours ≤ 3 cm from anal verge, ISR and after, transanal access platform insertion, and CO2 insufflation. Dissection starts from the presacral plane, the mesorectum is mobilized and the posterior dissection proceeded cephalic in the avascular presacral plane in accordance to TME principles. The dissection continues until peritoneal reflection is visualized and divided to achieve sigmoid colon mobilization. The specimen is extracted transanaly			CRM (-)	92.7%-96.7%
					“Intact” mesorectum	84%
					“Nearly complete” mesorectum	16%
					R0 resections achieved	94.6%
					No of retrieved lymphnodes	≥ 12

APPEAR: Anterior Perineal PlanE for Ultra-low Anterior Resection of the Rectum; APR: Abdominoperineal resection; CRM: Circumferential radial margin; CRT: Chemo-radio-therapy; EAS: External anal sphincter; IAS: Internal anal sphincter; ISR: Intersphincteric resection; LAR: Low anterior resection; TAMIS: TransAnal Minimally Invasive Surgery; TaTME: Transanal Total Mesorectal Excision; TEM: Transanal Endoscopic MicroSurgery; TME: Total mesorectal excision.