Apical lymph nodes at the root of the inferior mesenteric artery in distal colorectal cancer: an analysis of the risk of tumor involvement and the impact of high ligation on anastomotic integrity.

BACKGROUND: What level of arterial ligation is best in left-sided colon cancer and rectal cancer remains controversial. This study aims to assess the necessity and risk of high ligation from an oncological and technical perspective.
METHODS: The lymph nodes at the origin of the inferior mesenteric artery (IMA) were separated as apical nodes in all patients operated for distal colorectal cancer in our department. The number and status of the nodes were prospectively assessed, and demographic and tumor-related variables were evaluated as risk factors for apical tumor invasion. Anastomotic leaks were also evaluated.
RESULTS: A hundred and three patients (52 [50.5%] males, 60.3+/-12.9 years old) were included. The number of non-apical lymph nodes harvested was 14.5+/-7.1 with an additional 4.4+/-3.2 apical nodes at the high ligation site. Tumor invasion of apical nodes was observed in 6 (5.8%) patients. Two of these (1.9%) had no other positive nodes (skip metastases). Although none of the variables evaluated was found significant for predicting apical node positivity, tumor invasion was detected in 8.5 and 22.2% of patients with pT3 and pN2 cancers, respectively. Among patients, who had an anastomosis (n = 84, 81.6%), anastomotic leak was observed in 7(8.3%) and 1 (1.2%) of these patients required emergency relaparotomy. There was no mortality related to high ligation.
CONCLUSIONS: High ligation of IMA may be routinely performed in patients with distal colorectal cancer, since tumor invasion of apical lymph nodes is neither rare (>5%) nor predictable, and skip metastases may also occur. This is especially true in case of an advanced disease for which apical node positivity peaks. The anastomotic leak rate is less than 10%, and mortality is low after high ligation of IMA.