Inferior Mesenteric Artery Ligation Level and Anastomotic Leakage in Low Anterior Resection

Importance: The optimal level of inferior mesenteric artery (IMA) ligation during rectal cancer resection remains controversial because of potential trade-offs between anastomotic integrity and functional outcomes. Objective: To determine whether low ligation of the IMA reduces the rate of anastomotic leakage compared with high ligation in patients undergoing minimally invasive anterior resection for rectal cancer. Design, Setting, and Participants: This multicenter, prospective, randomized clinical trial enrolled patients with clinical stage I through III rectal cancer between July 2019 and August 2024. Patients scheduled for laparoscopic or robotic anterior resection were randomized to undergo either high or low ligation of the IMA. Interventions: High ligation (ligation at the root of the IMA) or low ligation (ligation distal to the origin of the left colic artery). Main Outcomes and Measures: The primary end point was the rate of anastomotic leakage. Secondary end points included surgical complications and functional outcomes (bowel, urinary, and sexual function) assessed at 12 months postoperatively. Results: Of 314 randomized patients, 293 were included in the modified intention-to-treat analysis (143 who received low ligation and 150 high ligation). The median (IQR) age was 64.0 (55.3-73.0) years; there were 102 female patients (34.8%) and 191 male patients (65.2%). Symptomatic anastomotic leakage occurred in 7 of 143 patients (4.9%) in the low-ligation group and 9 of 150 (6.0%) in the high-ligation group (risk ratio, 0.82; 95% CI, 0.31-2.13; P = .68). Overall 30-day postoperative morbidity was 14.0% (20/143 patients) vs 22.0% (33/150 patients) (P = .08). At 12 months, bowel function (mean [SD] Low Anterior Resection Syndrome [LARS] score, 15.8 [12.8] in the low-ligation group vs 17.3 [11.8] in the high-ligation group; P = .32) and the proportion of patients with major LARS (24/121 [19.8%] in the low-ligation group vs 25/130 in the high-ligation group [19.2%]; P > .99) were similar between groups; other functional and quality-of-life outcomes were also comparable. Conclusions and Relevance: In this randomized clinical trial, low ligation of the IMA did not significantly reduce the rate of anastomotic leakage compared with high ligation. Both techniques appear to be safe and feasible for minimally invasive rectal cancer surgery, with comparable complication rates and long-term functional outcomes. Trial Registration: Clinical Research Information Service identifier: KCT0003523.