By Caroline Helwick

When technically feasible, endoscopic en bloc resection is the preferred way to remove colorectal polyps with evidence of high-grade dysplasia or intramucosal cancer. Compared with piecemeal resection, en bloc removal poses less risk for malignant recurrence and surgical referral, according to the results of a study presented at the 2020 virtual meeting of the American College of Gastroenterology (abstract P1859).

“Our study highlights the clinical outcomes of endoscopic resection for colorectal polyps with high-grade dysplasia or intramucosal cancer. With advancements in endoscopic resection methods, en bloc resection should be the goal, as it maximizes the chance of a curative resection and decreases the risk of malignant recurrences,” Sonmoon Mohapatra, MD, a gastroenterology fellow at Saint Peter’s University Hospital, in New Brunswick, N.J., and lead author of the study, said. The research earned a Presidential Poster Award at the ACG meeting.

Benign polyps with high-grade dysplasia or intramucosal cancer can be completely removed by endoscopic resection, but malignant recurrence is of significant concern. Whether the type of resection—piecemeal versus en bloc—affects outcomes has not been established and was the question posed by the researchers.

In a retrospective chart review, Mohapatra and her colleagues identified 196 patients who underwent endoscopic resection for colorectal polyps with high-grade dysplasia or intramucosal cancer at two academic centers from 2005 to 2019. They examined clinical, endoscopic and pathologic characteristics, and adjusted for potential censoring bias.

They found that 66 (33.6%) lesions with high-grade dysplasia or intramucosal cancer were resected en bloc, and 130 (66.3%) were resected piecemeal. Polyps resected piecemeal were larger (22.8 vs. 15.1 mm; P<0.0001), more likely to be sessile (P<0.0001) and right-sided (P<0.0001), and more likely to be referred for surgery (8.6% vs. 0%) than en bloc resection.

Adverse events (delayed bleeding, post-polypectomy syndrome) occurred in four patients, including one following en bloc and three following piecemeal resection.

High Recurrence Risk

A total of 31 recurrences occurred over a mean follow-up period of 21 months. Benign adenomas were 11 times more likely to occur after piecemeal versus en bloc resection (hazard ratio, 10.8; P=0.019), Mohapatra reported.

The researchers identified four recurrences of high-grade dysplasia/intramucosal cancer during the study period, all among the patients who underwent piecemeal resection (log-rank P=0.132), yielding a number needed to treat of 4.9 to prevent one malignant recurrence (95% CI, 2.8-19.2). All patients were referred for surgery, while the remainder of the 31 recurrences (84%) were managed with repeat endoscopic resection.