Effect of Laparoscopic-Assisted Resection vs Open Resection of Stage II or III Rectal Cancer on Pathologic Outcomes: The ACOSOG Z6051 Randomized Clinical Trial

High-quality total mesorectal excision (TME) is central to rectal cancer treatment. This trial investigated whether laparoscopic resection was not importantly worse than conventional open resection in terms of the quality of TME. The study was designed using a noninferiority approach with a novel composite outcome called “successful resection” combining pathologic assessment of distal margin, circumferential resection margin, and plane of mesorectal excision. This was a multicenter randomized noninferiority clinical trial including 486 patients with clinically stage II or III rectal cancer treated with neoadjuvant chemoradiotherapy/radiotherapy. Patients underwent laparoscopic or open rectal resection based on randomization using standard approaches to TME. All surgeons were credentialed. Successful resection occurred in 81.7% (95% CI 76.8 to 86.6) in the laparoscopic group and 86.9% (95% CI 82.5 to 91.4) in the open group with a difference of −5.3% (1-sided 95% CI −10.8 to ) and p-value for noninferiority of 0.41. Because the 1-sided 95% confidence interval includes the noninferiority margin of 6%, the results are inconclusive regarding noninferiority of laparoscopic compared to open rectal resection. In subsequent meta-analyses, laparoscopy was noninferior to open surgery on pathologic outcomes, and longer-term survival outcomes were not different between approaches.