Outcomes of transanal total mesorectal excision compared to laparoscopic total mesorectal excision: A meta-analysis of randomized controlled trials

Background: Transanal dissection is increasingly used in laparoscopic surgery for total mesorectal excision of lower rectal cancers. Several studies compared outcomes of laparoscopic total mesorectal excision with and without transanal dissection, yet there is a paucity of high-quality evidence. This meta-analysis aimed to provide a pooled comparative analysis of outcomes of laparoscopic total mesorectal excision with and without transanal dissection based on evidence from randomized controlled trials. Methods: This Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2022–compliant systematic review of randomized controlled trials compared laparoscopic total mesorectal excision with and without transanal dissection. PubMed, Scopus, and Web of Science were searched through March 2023. The Medical Subject Headings terms used in the search were Rectal neoplasms, Proctectomy, Laparoscopy, and Transanal. The main outcomes included operative and pathologic outcomes. The risk of bias was assessed using the Risk of Bias version 2 tool, and certainty of the evidence was graded using the Grading of Recommendations Assessment, Development, and Evaluation approach. The primary study outcome was conversion to open surgery. Results: Four randomized controlled trials (1,339 patients; median age 61.2 years) were included; 671 patients underwent laparoscopic total mesorectal excision with transanal dissection, and 668 underwent laparoscopic total mesorectal excision without transanal dissection. Both groups were similar in age, body mass index, and disease stage, but the laparoscopic total mesorectal excision with transanal dissection group had a higher male-to-female ratio, received neoadjuvant therapy and had a hand-sewn anastomosis more often. Patients who underwent laparoscopic total mesorectal excision with transanal dissection had lower conversion rates (odds ratio = 0.179; P = .001), a higher likelihood of achieving complete total mesorectal excision (odds ratio = 1.435; P = .025), and fewer harvested lymph nodes (weighted mean difference = –1.926; P = .035). The groups had similar operative times (weighted mean difference = –3.476; P = .398), total complications (odds ratio = 0.94; P = .665), major complications (odds ratio = 1.112; P = .66), anastomotic leak (odds ratio = 0.67; P = .432), positive circumferential resection margin (odds ratio = 0.549; P = .155), and positive distal margins (odds ratio = 0.559; P = .171). Conclusion: Laparoscopic total mesorectal excision with transanal dissection was associated with lower odds of conversion to open surgery, greater likelihood of achieving complete total mesorectal excision, and fewer harvested lymph nodes than laparoscopic total mesorectal excision without transanal dissection.