Operative safety and oncologic outcomes in rectal cancer based on the level of inferior mesenteric artery ligation: a stratified analysis of a large Korean cohort

PURPOSE: To compare high and low inferior mesenteric artery (IMA) ligation in a large number of patients, and investigate the short-term and long-term outcomes. METHODS: This retrospective study compared outcomes between high IMA ligation and low IMA ligation with dissection of lymph nodes (LNs) around the IMA origin. A total of 1,213 patients underwent elective low anterior resection with double-stapling anastomosis for stage I–III rectal cancer located ≥6 cm from the anal verge (835 patients underwent IMA ligation at the IMA origin; 378 patients underwent IMA ligation directly distal to the root of the left colic artery along with dissection of LNs around the IMA origin). RESULTS: There was no difference in anastomotic leakage rate between groups. The 2 groups did not significantly differ in intraoperative blood loss, perioperative complications, total number of harvested LNs, and metastatic IMA LNs. However, more metastatic LNs were harvested in the high-tie than in the low-tie group (1.3 ± 2.9 vs. 0.8 ± 1.9, P = 0.002), and the incidence of positive pathologic nodal status was higher in the high-tie group (37.9% vs. 28.6%, P = 0.001). The 5-year local recurrence-free and metastasis-free survival rates were similar between groups, as were the 5-year overall and cancer-specific survival rates. CONCLUSION: Low IMA ligation with dissection of LNs around the IMA origin showed no differences in anastomotic leakage rate compared with high IMA ligation, without affecting oncologic outcomes. High IMA ligation did not seem to increase the number of total harvested LNs, whereas the ratio of metastatic apical LNs were similar between groups.