Efficacy and safety of transanal endoscopic operation in rectal tumors: a meta-analysis and systematic review

Abstract Background This meta-analysis aims to systematically evaluate the safety, efficacy, and outcomes of the Transanal Endoscopic Operation (TEO ® ) for the management of benign and malignant rectal lesions. Methods The research was registered with the International Prospective Register of Systematic Reviews (PROSPERO; CRD42024548115). A search in MEDLINE, Embase, Scopus, and Cochrane Central databases was conducted from the inception to August 2024. All participants aged 18 years and older who underwent TEO for management of rectal lesions, were included. Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA) guidelines were followed, selecting only randomized controlled trials, cohort studies, and case series. A random-effects model was used for single-arm analyses. Results A total of 628 patients underwent 634 TEO procedures across the included studies. The pooled proportion of female patients was 42.6%, with a mean age of 65.11 years. The mean tumor size was 35.63 mm, with an average distance of 6.97 cm from the anal verge. Adenomas (48.7%) and adenocarcinomas (30.6%) constituted the most frequent histological findings. En bloc resection was accomplished in 93.6% of procedures. Conversion rates were 3.8% converting to laparoscopy and 2.9% to open surgery. The recurrence rate during follow-up was 8.2%. Overall mortality reached 4.3% while overall mortality due to TEO was 1.4%. Postoperative complications occurred in 20.7% of patients. Reoperations were required in 15.3% of cases, mainly due to complications, positive margins, or understaged tumors. Conclusions This meta-analysis demonstrates that TEO is characterized by high rates of en bloc resection, low conversion rates, and acceptable morbidity. Recurrence and mortality rates remained low, and most complications were manageable. The available evidence, drawn from the largest pooled cohort reported to date, supports TEO as an established, standard minimally invasive technique for the local treatment of appropriately selected rectal lesions. However, these findings are based on a limited number of predominantly nonrandomized studies with substantial heterogeneity in clinicopathologic characteristics, follow-up duration, and outcome reporting. Further high-quality comparative studies are warranted to better define its role relative to alternative local excision techniques and radical surgery, particularly regarding long-term oncologic outcomes.