Low Versus High Ligation of Inferior Mesenteric Artery in Rectal and Sigmoid Cancers: A Systematic Review, Meta-analysis, and Trial Sequential Analysis of Randomized Controlled Trials.

[BACKGROUND] The optimal level of the inferior mesenteric artery (IMA) ligation in rectosigmoid cancer surgery remains controversial, with ongoing debate about the balance between oncologic adequacy and anastomotic integrity. This meta-analysis compared high ligation (HL) versus low ligation (LL) of IMA in terms of postoperative and long-term oncologic outcomes using randomized controlled trials (RCTs).

[MATERIALS AND METHODS] A systematic search of 5 databases (inception-May 2025) identified 15 RCTs comparing LL and HL in rectal or sigmoid cancer. Primary outcomes included 5-year overall survival (OS), disease-free survival (DFS), overall complications, and anastomotic leak (AL) rates. Secondary outcomes included lymph node yield, operative time, and blood loss. Trial sequential analysis (TSA), risk of bias, and Grading of Recommendations Assessment, Development, and Evaluation (GRADE) assessment were performed.

[RESULTS] A total of 2576 patients were included. LL significantly improved 5-year OS (HR 0.69; 95% CI 0.50-0.96; p = 0.026) and reduced AL rates (OR 0.71; 95% CI 0.51-1.00; p = 0.050), without compromising DFS or lymph node yield. TSA confirmed the OS benefit and robustness of AL reduction, with the cumulative Z-curve crossing both the conventional and trial sequential monitoring boundaries for benefit. LL was not associated with increased overall complications, operative time, or blood loss. GRADE ratings indicated moderate-to-high certainty for key outcomes.

[CONCLUSIONS] Low ligation of the IMA offers a survival advantage and reduced anastomotic leak risk without compromising oncologic safety. These findings support LL as the preferred approach in rectosigmoid cancer surgery, though further RCTs are warranted to strengthen the evidence for certain outcomes.