Comparing the Surgical Outcomes of Intersphincteric Resection (ISR) and Transanal Total Mesorectal Excision (TATME) in Rectal Cancer: A Meta-Analysis

Rectal cancer management has evolved significantly with the introduction of sphincter-preserving techniques, particularly intersphincteric resection (ISR) and transanal total mesorectal excision (TATME), aimed at improving oncologic safety while maintaining functional outcomes. Despite increasing use, comparative evidence remains limited. This meta-analysis evaluated surgical and oncologic outcomes of ISR versus TATME in patients with low rectal cancer. A comprehensive search of PubMed, Scopus, CENTRAL, ProQuest, and Google Scholar identified eligible randomized and observational studies published between January 2016 and March 2025. Five studies, including one randomized controlled trial, two propensity-matched analyses, and two comparative cohort studies, comprising 1,630 patients (ISR=802; TATME=828), were included. Pooled data demonstrated no significant difference in anastomotic leakage rates between ISR and TATME (OR=0.86; 95% CI: 0.58-1.26; p=0.42) and similar circumferential resection margin positivity (OR=0.91; 95% CI: 0.62-1.33; p=0.62), indicating comparable oncologic quality. Local recurrence rates were also equivalent (OR=0.94; 95% CI: 0.64-1.39; p=0.77). However, TATME demonstrated a significantly lower rate of postoperative complications (OR=0.61; 95% CI: 0.44-0.84; p=0.003), suggesting improved short-term recovery. Conversely, TATME required longer operative time compared with ISR (OR=1.74; 95% CI: 1.30-2.32; p=0.0002), likely reflecting technical demands and the learning curve. Overall, both techniques achieved comparable oncologic safety, with TATME offering reduced postoperative morbidity at the cost of increased operative duration. These findings support TATME as a safe and effective alternative to ISR in specialized centers with appropriate expertise. Future large-scale randomized trials with long-term follow-up are required to validate functional outcomes and refine patient selection.