Supplementary Material for: Level of inferior mesenteric artery ligation in sigmoid colon and rectal cancer surgery: analysis of apical lymph node metastasis and recurrence

Introduction: Whether high or low ligation of the inferior mesenteric artery (IMA) is optimal for treating sigmoid colon and rectal cancers is controversial. The present study aimed to compare outcomes of high and low ligation of the IMA and determine the adequate extent of IMA lymph node dissection. Methods: Subjects were 455 consecutive stage I-III colorectal cancer patients who underwent curative surgery between 2011 and 2019. We assessed the association between the level of IMA ligation and overall survival and recurrence-free survival (RFS) by using propensity score matching analysis. Clinicopathological features of IMA lymph node metastasis and recurrence patterns were analyzed. Results: After propensity score matching, the low ligation group had a significantly worse prognosis than that of the high ligation group for RFS (P=0.039). Positive IMA lymph nodes were associated with pathological T3 or T4 stage and N2 stage. IMA lymph node recurrences in the high ligation group occurred at the left and superior sides of the IMA root. In contrast, all recurrences in the low ligation group occurred at the left colic artery bifurcation. Conclusion: High ligation of IMA is oncologically safe. However, even with high ligation, care must be taken to ensure adequate lymph node dissection.

引言：肠系膜下动脉（inferior mesenteric artery, IMA）的高位结扎与低位结扎用于治疗乙状结肠癌及直肠癌是否为最优方案，目前仍存在争议。本研究旨在对比IMA高位结扎与低位结扎的治疗结局，并明确IMA淋巴结清扫的合理范围。
方法：研究对象为2011年至2019年间接受根治性手术的455例连续入组的I~III期结直肠癌患者。本研究采用倾向得分匹配分析，评估IMA结扎水平与总生存期及无复发生存期（recurrence-free survival, RFS）之间的关联，并分析IMA淋巴结转移的临床病理特征及复发模式。
结果：经倾向得分匹配后，低位结扎组的无复发生存期预后显著差于高位结扎组（P=0.039）。IMA淋巴结阳性与病理T3或T4分期及N2分期呈显著相关。高位结扎组的IMA淋巴结复发灶位于IMA根部的左侧及上方区域；与之相反，低位结扎组的所有复发灶均位于左结肠动脉分叉处。
结论：从肿瘤学角度而言，IMA高位结扎是安全的。但即便采用高位结扎，仍需注意确保足够范围的淋巴结清扫。