Perioperative safety evaluation of intersphincteric resection combined with rectal eversion and total extra-abdominal resection: a prospective randomized controlled trial.

Background: Colorectal cancer remains a significant global health burden, with low rectal tumors posing unique surgical challenges due to their proximity to the anal verge. Traditional abdominoperineal resection (APR) compromises quality of life with permanent colostomy, while sphincter-preserving techniques like laparoscopic intersphincteric resection (L-ISR) face technical limitations. This study evaluates the safety and efficacy of a novel technique - ISR combined with rectal eversion and total extra-abdominal resection (ISRER) - aimed at reducing anastomotic complications, and enhancing anal preservation in anatomically challenging patients.

Methods: This was a prospective randomized controlled, unmasked, parallel group trial in Henan Provincial People's Hospital. Intraoperative peritoneal lavage cytology and bacterial culture were performed to assess tumor cell shedding and contamination. Outcomes included distal margin positivity, anal preservation rate, postoperative complications, hospital costs,30-day readmission rates and postoperative stay.

Results: All 74 patients with low rectal cancer (3-5 cm from the anal verge) between March 2024 and March 2025. Patients were randomly stratified into ISRER (n = 35) and laparoscopic ISR (L-ISR) (n = 39) groups. No tumor cells or bacterial contamination were detected in peritoneal lavage cytology or cultures. Both groups achieved 100% R0 resection (distal margin negativity). The ISRER group demonstrated a significantly higher anal preservation rate (94.3 vs. 71.8%, P = 0.011) with comparable postoperative complications (2.9 vs. 2.6%, P = 0.735), 30-day readmission rates (2.9 vs. 2.6%, P = 0.938), and hospitalization costs (62,540 vs. 64,937 CNY, P = 0.915). Median postoperative stay was marginally longer in the ISRER group (10 vs. 9 days, P = 0.135), while gastrointestinal recovery and inflammatory markers showed no intergroup differences.

Conclusion: ISRER is a safe and technically feasible sphincter-preserving approach for low rectal cancer, offering superior anal retention without compromising oncological safety or increasing complications.