The SMART Trial: Modified Single-Stapled Anastomosis in Laparoscopic or Robotic Low Anterior Resection for Rectal Cancer

Anastomotic leakage is one of the most serious complications after low anterior resection (LAR) for rectal cancer. This complication can lead to infection, reoperation, prolonged hospitalization, higher medical costs, and worse long-term oncologic outcomes. Although laparoscopic and robotic surgery have improved short-term recovery compared with open surgery, the risk of anastomotic leakage remains a major concern.

The most commonly used reconstruction method during minimally invasive LAR is the double-stapled technique (DST). In DST, the rectum is transected with a linear stapler and then reconnected with a circular stapler. This creates an intersection between two staple lines, a known weak point that may be prone to leakage due to structural and ischemic vulnerability.

The modified single-stapled technique (MST) eliminates this intersection. Before applying the circular stapler, the two ends of the linear staple line on the rectal stump are brought together using a simple suture. This results in a single, centered staple line that the circular stapler incorporates completely into the anastomosis. Early studies, including a previous randomized trial, suggest that MST significantly reduces anastomotic leakage compared with DST.

This multicenter randomized controlled trial aims to provide high-quality evidence on the effectiveness of MST in reducing anastomotic leakage in patients undergoing laparoscopic or robotic LAR for rectal cancer. A total of 440 adult patients will be enrolled across multiple high-volume university hospitals in South Korea. Participants will be randomly assigned in a 1:1 ratio to receive MST or DST. Randomization will be stratified by sex, neoadjuvant treatment, and study center.

To ensure consistent surgical quality, all participating colorectal surgeons will complete a pre-trial standardization workshop and submit unedited surgical videos for competency review. All surgical procedures will follow standardized steps, and perioperative care will be based on established Enhanced Recovery After Surgery (ERAS) protocols.

The primary outcome is the rate of anastomotic leakage within one month after surgery. All participants will undergo routine abdominopelvic CT scans within this time window to detect both symptomatic and asymptomatic leaks. Secondary outcomes include postoperative complications, operative time, distal resection margin length, hospital stay, and long-term oncologic outcomes such as recurrence and survival. If MST is shown to be superior to DST, this study may support a simple, low-cost, and easily adoptable modification to current surgical practice. MST does not require additional equipment or complex training, making it a potentially valuable technique that can improve patient safety and surgical outcomes in rectal cancer care across diverse clinical settings.