Pathological outcomes of transanal versus laparoscopic total mesorectal excision for rectal cancer: a systematic review with meta-analysis

Hong-Peng Jiang, Yan-Sen Li, Bo Wang, Chang Wang, Fan Liu, Zhan-Long Shen, Ying-Jiang Ye, Shan Wang

Since 2010, comparative studies on transanal and laparoscopic total mesorectal excision (TME) have been published and it remains unclear about the oncological benefit from transanal total mesorectal excision (taTME). We have searched English databases to identify all taTME studies published between January 2010 and August 2017. Pathological outcomes included circumferential resection margin (CRM), positive CRM (< 1 M), length of distal resection margin (DRM), positive DRM, quality of mesorectum (complete mesorectum), harvested lymph node, and length of the specimen. Odds ratios (ORs) were calculated for dichotomous outcomes and weighted mean differences (WMDs) for continuous outcomes. We have included ten studies comprising of 762 patients. Compared with laparoscopic TME, taTME had a longer CRM (WMD, 0.833; 95% CI 0.366-1.299; P < 0.001), a lower positive rate of CRM (OR, 0.505; 95% CI 0.258-0.991; P = 0.047), and a longer DRM (WMD, 6.261; 95% CI 1.049-11.472; P = 0.019). There were no significant differences in other pathological outcomes. Both cumulative meta-analysis and sensitivity analysis were unable to detect potential sources of the heterogeneity in DRM. There was no evidence of publication bias. This meta-analysis revealed that taTME had more advantages on positive CRM, CRM, and DRM compared with laparoscopic TME. Compared with laparoscopic TME, more benefits of taTME on pathological outcomes remained undetected. The current findings are all based on observational studies, RCTs with adequate power are required.