The significance of anatomical variation of the inferior mesenteric artery and its branches for laparoscopic radical resection of colorectal cancer: a review

Currently, high or low ligation of the inferior mesenteric artery (IMA) is a controversial issue in laparoscopic radical surgery for colorectal cancer. High or low ligation of the IMA has both advantages and disadvantages, and the level of ligation during the left colon and/or rectum resection has been a dilemma for surgeons. One important factor influencing the surgeon's decision to ligate the IMA in a high or low position is the anatomical type of the IMA and its branches. Some studies confirm that the anatomy of the IMA and its branches is critical to the anastomotic blood supply and, therefore, influences the choice of surgical approach (level of ligation of the IMA). However, many vascular variations in the anatomy of the IMA and its branches exist. Herein, we have summarized the anatomical types of the IMA and its branches, finding that the classification proposed by Yada et al. in 1997 is presently accepted by most scholars. Based on Yada's classification, we further summarized the characteristics of the IMA's various anatomical types as a guide for high or low ligation in radical colorectal cancer surgery.

[Chinese expert consensus on radical resection of rectal cancer with preservation of left colonic artery (2021 edition)]

The preservation of left colonic artery (LCA) has been accepted by more and more surgeons in the radical resection of rectal cancer, but whether it can reduce anastomotic complications and affect the oncology efficacy remains controversial. This consensus elaborates the significance, anatomical structure, key points of operation techniques, indications and contraindications, and surgical approaches of LCA preservation. Each statement and recommendation was recognized by most experts in the field of colorectal surgery. The purpose of this consensus is to improve the cognitive level of Chinese colorectal surgeons on LCA preservation, so as to standardize the surgical strategies and methods of LCA preservation and furthermore practice, and promote it. The pending issues in this consensus need further high-quality clinical studies.

[Anatomical controversies involved in radical resection of rectal cancer]

The concept of total mesorectal resection provides a quality control standard that can be followed for radical resection of rectal cancer, but some anatomical problems are still controversial. Compared with traditional open surgery, laparoscopic radical rectal surgery has better surgical vision, better neurological protection, better operating space. However, if the surgeon has insufficient understanding of the anatomy, collateral damage may occur, such as uncontrollable bleeding during the operation, postoperative urination and defecation dysfunction and so on. Based on the interpretation of the researches at home and abroad, combined with the clinical experience, we elucidate some associated issues, including anatomic variation of inferior mesenteric vessels, the controversy of inferior mesenteric artery ligation plane, the controversy of lymph node dissection in No. 253, the anatomical variation of middle rectal artery, and the anatomical controversy of lateral lymph node dissection in rectal cancer, in order to provide better cognitive process for the clinical front-line surgeons.

The feasibility of laparoscopic TSME preserving the left colic artery and superior rectal artery for upper rectal cancer

Background

Laparoscopic tumor-specific mesorectal excision (TSME) preserving the left colic artery and superior rectal artery is still a technically challenging procedure. We conducted this study to demonstrate the feasibility of this procedure for upper rectal cancer.

Methods

A total of 184 patients with upper rectal cancer were retrospectively analyzed in our cancer center between April 2010 and April 2017. These patients were treated with either laparoscopic TSME (n = 46) or laparoscopic total mesorectal excision (TME) (n = 138). In the TSME group, the left colonic artery and superior rectal artery were preserved while they were not in the TME group.

Results

The operation time in the TSME group was longer than that in the TME group (218.56 ± 35.85 min vs. 201.13 ± 42.65 min, P = 0.004). Furthermore, the number of resected lymph nodes in the TSME group was greater than that in the TME group (19.43 ± 9.46 vs. 18.03 ± 7.43, P = 0.024). The blood loss between the TSME and TME groups was not significant. No mortality occurred in either the TSME or TME groups. One patient in the TME group underwent conversion to laparotomy. The total postoperative complication rates in the TSME and TME groups were 8.7% and 17.4%, respectively. There was no difference in severe complications between the two groups (anastomotic leakage and stenosis).

Conclusions

Laparoscopic TSME preserving the left colic artery and superior rectal artery can be safely conducted for upper rectal cancer.