Low or High Ligation of the Inferior Mesenteric Artery With Apical Lymph Node Dissection in Rectal Cancer Laparoscopic Surgery: A Prospective, Multi-Center, Randomized, Open-Label, Parallel Group, Non-Inferiority Clinical Trial (LAND)

According to the report of World Health Organization 2015, the morbility and mortality of colorectal cancer (CRC) are rising all over the world. Although the technique gets great approval in CRC surgical treatment in the recent years, such as TME protocol, neoadjuvant and laparoscopy technique, the complication of anastomosis leakage and nerve damage are still to be solved.

Laparoscopy colon surgery is accepted worldwide in the recent years. But there is still argument on the effect of laparoscopy rectal surgery. Laparoscopy has advantages on showing the inferior mesenteric artery, protection of autonomic nerve, low rectal anastomosis, and total mesorectum excision. However, debate on where is the best level of IMA ligation and whether splenic flexure be debonded never ends. This study is going to give a clear and definite answer to how and why surgeons should deal with the IMA in laparoscopy rectal surgery.

The ligation level of IMA affects on hypogastric and pelvic nerve, leads to disorder of sexual and urination functions. What's more, it also have affection on the apical lymph node (No.253) harvesting and the blood supplement of proximal colon. Former studies have proved that the blood supplement and tension of anastomosis leads to leakage after surgery. Meanwhile, the ligation level of IMA is the key point on it.

The former study comes from the sixth affiliated hospital found that the mistake of ligation level of IMA happened because of the poor touching and explosion with laparoscopy. The distance from the root of IMA to left colic artery (DRL) vary between 19mm and 64mm. When surgeon made mistake during ligation, it led to the insufficient resection of apical lymph node. Further more, affect the long-term survival. Besides, there are 4 different types of IMA according to the relationship between the left colic artery, sigmoid artery and superior rectal artery. These branches will confuse surgeon on how to deal with them. 3D reconstruction of abdominal pelvic CT is able to show the length of DRL, IMA types and apical lymph nodes clearly. With these technique, the investigators can preserve the left colic artery and resect apical lymph nodes precisely.

In the past studies, high or low ligation takes advantage on both side. But none of them comes from retrospective clinical trail. Some author believe that high ligation do better in resection of apical lymph nodes, release the tension of anastomosis, providing precise tumor staging. On the other side, some authors consider that high ligation may cut down blood supplement, rise the incident of anastomosis leakage (AL). so they prefer low ligation to the high. Some studies show that there are no long term survival difference between high and low ligation on IMA in laparoscopy rectal resection. So whether high ligation is necessary, still to be proved.