[Comparison of effect of different medial boundaries in laparoscopic right hemicolectomy: a meta-analysis]

Objective: To investigate and compare the clinical efficacy and prognosis of D3 lymphadenectomy/complete mesocolic excision in treatment of right colon cancer with different medial boundaries. Methods: We searched The Cochrane Library, Pubmed, Embase, CBM, VIP, CNKI, and WanFang data bases for superior mesenteric artery (SMA)-oriented and superior mesenteric vein (SMV)-oriented D3 lymphadenectomy/complete mesocolic excision from inception to December, 2023. The resultant data were submitted to meta-analysis using RevMan 5.3 software. Results: In total, we identified nine eligible studies involving 2467 patients. The SMA group had 982 patients and the SMV group had 1 485 patients. Meta-analysis revealed no significant differences in intraoperative bleeding volume, postoperative time to passage of flatus, or postoperative drainage volume between the two studied approaches. The durations of surgery and of postoperative hospital stay were both significantly longer in the SMA than SMV group (weighted mean difference [WMD]=17.70, 95%CI: 6.90-28.50, P=0.001; WMD=0.40, 95%CI: 0.07-0.72, P=0.020, respectively). Furthermore, the rate of postoperative complications was greater in the SMA than SMV group. For example, the incidences of postoperative chyle leakage and diarrhea were significantly higher in the SMA than SMV group, (OR=1.25, 95%CI: 1.01-1.54, P = 0.040; OR=3.60, 95%CI: 2.39-5.41, P < 0.001; OR=2.13, 95%CI: 1.10-4.11, P = 0.020, respectively). In terms of oncological efficacy, the total number of lymph nodes dissected and the number of positive lymph nodes in the SMA group were significantly higher than in the SMV group (WMD=2.76, 95%CI:1.22-4.31, P < 0.001, WMD=0.59, 95%CI: 0.06-1.12, P = 0.030). Conclusion: Laparoscopic surgery for right colon cancer, using the left margin of the SMA as the medial boundary for dissection is associated with a higher risk of postoperative complications, such as chyle leakage and diarrhea, than is using the superior mesenteric vein as the medial boundary. The durations of surgery and postoperative hospital stay are longer. SMA left margin dissection has significant oncological advantages, including a higher total number of harvested lymph nodes and of positive lymph nodes.