Level of vascular ligation and association with oncological expediency in sigmoid and rectal cancer

Introduction: The techniques and oncology feasibility of high vascular ligation of the inferior mesenteric artery along with their varieties – low tie (LT) and high tie (HT) techniques in left-sided colon and rectal cancer, were described more than 100 years ago by Miles and Moynihan. However, the relationship between the level of vascular ligation and the microperfusion of the proximal anastomosis segment, on the one hand, and the volume and quality of lymphatic dissection, on the other, are the subject of numerous clinical trials and discussions. The vegetative nerve spare in the different approaches is also included in a consideration. Despite the well-established modern standardization in conventional and laparoscopic left colon and rectal cancer surgery, some surgeons still do ligation at the a. rectalis superior level in rectal cancer, which contradicts modern oncology principles.Materials and Methods: Prospective non-randomized comparative cohort study of patients from the Department of Surgery in Alexandrovska University Hospital with cancer of the sigmoid colon or rectum in clinical stage I-III, operated by an open or laparoscopic approach over a 4-year period, stratified into two groups according to the level of ligation of the inferior mesenteric artery (IMA) and vein - high tie - at the site of the origin  (1 cm) from aorta and low tie - distal to the origin of the left colic artery. The comparative indicators included the anastomotic leakage rate, the number of lymph nodes harvested with a metastatic lymph node index, a 3-year disease-free survival (DFS), disease-related survival OS. The follow-up period was 12-48 months.Results: For the period 2014-2018 a total of 217 patients with cancer of the sigmoid colon or rectum underwent 169 laparoscopic and 48 open surgeries. The distribution was as follows: 69% high ligation compared to 31% low ligation; 52 in an emergency or delayed emergency manner; 58% male and 42% female, mean age 64 ± 0.8 years; 56% in clinical stage III, 40% in II and only 4% in clinical stage I, relatively evenly distributed in the two target groups. There were wide variations in the number of lymph nodes harvested from the specimen (n = 4 to 22) for both groups without significant differences in the metastatic index. There was no statistically significant difference in the incidence of anastomotic leaks for both groups (3.8% for HT versus 3.0% for LT). With respect to the 3-year disease-free interval, there were also significant differences - 81.2% (HT) and 79.4% (LT) and the overall survival rate of 79.1% (HT) compared to 77.2% (LT) with a 72% follow-up coefficient.Discussion: The findings of this study are broadly consistent with those published so far and analyzed in three systematic reviews - the last one in 2018. This indicates that no statistically significant difference between high and low vascular ligation has been identified for the most important comparative indicators. It is extremely important to discuss several technical issues at present - contemporary problems requiring future high-quality clinical trials: the necessity and means of implementing left colic flexure mobilization in both types of vascular ligation with the lack of standardization; adequate and accurate identification of a correct cleavage plane of the dissection with differentiation of target vascular areas, avoiding erroneous entry into the sigmoid mesentery along with separate ligation of sigmoid vessels - oncologically inappropriate; sequence and level of ligation of the lower mesenteric vein with wide variations; pathoanatomic processing of the specimen with adequate isolation and examination of the removed lymph nodes, respectively adequacy of the pathohistological N-staging as well as the quality of the mesorectal excision; the need for stage control of the microvascular perfusion of the anastomosis segments by ICG fluorescence on the already validated global methods (hence the prevention of anastomotic leaks); progress in the importance and technical feasibility of low tie vascular ligation + perivascular lymph dissection to the IMA origin, and complete mesocolic excision (CME) in colon carcinoma (similar to TME in the rectal), the subject of more and more current studies; the specifics and advantages of robotic surgery of left-sided colon and rectal cancer with respect to accuracy of vascular and lymphatic dissection