Modified single-stapled anastomosis in laparoscopic or robotic low anterior resection for rectal cancer: protocol for a multicentre randomised controlled trial.

Anastomotic leakage remains one of the most serious complications after low anterior resection for rectal cancer. The modified single-stapled technique (MST) eliminates the intersection between linear and circular staple lines and may reduce leakage compared with the conventional double-stapled technique (DST). This trial aims to determine whether MST reduces anastomotic leakage in patients undergoing laparoscopic or robotic low anterior resection. This is a multicentre, parallel-group and superiority randomised controlled trial conducted in six tertiary hospitals in South Korea. A total of 450 patients undergoing laparoscopic or robotic low anterior resection for rectal cancer will be randomised in a 1:1 ratio to MST or DST. Randomisation will be stratified by sex and neoadjuvant treatment. The primary outcome is anastomotic leakage within 30 days after surgery, confirmed by clinical findings and routine postoperative abdominopelvic CT. Secondary outcomes include additional distal resection margin length, local recurrence, 3-year disease-free survival and overall survival. Analyses will follow the intention-to-treat principle. The study was approved by the Institutional Review Board of Korea University Anam Hospital (2025AN0114). Results will be disseminated through peer-reviewed journals and scientific meetings. NCT07376980.