[Meta-analysis for high-risk factor of anastomotic leakage after anal-preserving surgery for rectal cancer]

To systematically evaluate the effect of defunctioning stoma, preoperative radiotherapy, and level of inferior mesenteric artery (IMA) ligation on the postoperative anastomotic leakage in rectal cancer by meta-analysis.

Randomized controlled trials (RCT) published before December 2017 regarding the effects of defunctioning stoma, preoperative radiotherapy, and level of inferior mesenteric artery ligation on the postoperative anastomotic leakage in rectal cancer were searched from PubMed, Embase, Scopus, Cochrane Library, CNKI, Wanfang database, meanwhile open data in unpublished trials from clinicaltrials.gov were retrieved. Associated data were screened according to standard and their quality was evaluated strictly. Review manager 5.3 software was used to perform meta-analysis with data. Random effect model based on DerSimonian and Laird method was applied. Heterogenicity among trials was estimated with Chi-square test.

Twenty articles were included in the meta-analysis. The overall incidence of anastomotic leakage was 7.0%(488/7004). The incidence of anastomotic leakage in the defunctioning stoma group and non-defunctioning stoma group was 5.2%(24/459) and 17.3%(77/445) respectively. The incidence of anastomotic leakage in the radiotherapy group and non-radiotherapy group was 6.5%(188/2900) and 6.1%(179/2946) respectively. The incidences of anastomotic leakage in the low and high IMA ligation groups was 4.7%(6/129) and 11.2%(14/125) respectively. Meta-analysis showed that the incidence in defunctioning stoma group was significantly lower than that in non-defunctioning stoma group (RR:0.33, 95%CI:0.21-0.50, P<0.00001); the incidences between radiotherapy group and non-radiotherapy (RR:1.05, 95%CI: 0.80-1.38, P=0.72), and between low IMA ligation group and high IMA ligation group (RR:0.50, 95%CI:0.20-1.23, P=0.13) were not significantly different. Funnel figure drawn with RCTs about defunctioning stoma and preoperative radiotherapy revealed no significant publication bias existed within included studies.

Defunctioning stoma can effectively prevent the occurrence of postoperative anastomotic leakage, whereas the preoperative radiotherapy and high IMA ligation may not increase the risk of anastomotic leakage.