Meta-analysis of transanal vs laparoscopic total mesorectal excision of low rectal cancer: Importance of appropriate patient selection

BACKGROUND: Achieving a clear resection margins for low rectal cancer is technically challenging. Transanal approach to total mesorectal excision (TME) was introduced in order to address the challenges associated with the laparoscopic approach in treating low rectal cancers. However, previous meta-analyses have included mixed population with mid and low rectal tumours when comparing both approaches which has made the interpretation of the real differences between two approaches in treating low rectal cancer difficult. AIM: To investigate the outcomes of transanal TME (TaTME) and laparoscopic TME (LaTME) in patients with low rectal cancer. METHODS: A comprehensive systematic review of comparative studies was performed in line with Preferred Reporting Items for Systematic Reviews and Meta-Analyses standards. Intraoperative and postoperative complications, anastomotic leak, R0 resection, completeness of mesorectal excision, circumferential resection margin (CRM), distal resection margin (DRM), harvested lymph nodes, and operation time were the investigated outcome measures. RESULTS: We included twelve comparative studies enrolling 969 patients comparing TaTME (n = 969) and LaTME (n = 476) in patients with low rectal tumours. TaTME was associated with significantly lower risk of postoperative complications (OR: 0.74, P = 0.04), anastomotic leak (OR: 0.59, P = 0.02), and conversion to an open procedure (OR: 0.29, P = 0.002) in comparison with LaTME. Moreover, the rate of R0 resection was significantly higher in the TaTME group (OR: 1.96, P = 0.03). Nevertheless, TaTME and LaTME were comparable in terms of rate of intraoperative complications (OR: 1.87; P = 0.23), completeness of mesoractal excision (OR: 1.57, P = 0.15), harvested lymph nodes (MD: -0.05, P = 0.96), DRM (MD: -0.94; P = 0.17), CRM (MD: 1.08, P = 0.17), positive CRM (OR: 0.64, P = 0.11) and procedure time (MD: -6.99 min, P = 0.45). CONCLUSION: Our findings indicated that for low rectal tumours, TaTME is associated with better clinical and short term oncological outcomes compared to LaTME. More randomised controlled trials are required to confirm these findings and to evaluate long term oncological and functional outcomes.