Comparison of Endoscopic Therapies for Small Rectal Neuroendocrine Tumors: Endoscopic Muscularis Superficialis Dissection Versus Endoscopic Submucosal Dissection

ABSTRACT Background and Aim Rectal neuroendocrine tumors (rNETs) often exhibit submucosal tumor‐like growth. While endoscopic submucosal dissection (ESD) is widely used, it carries a risk of positive vertical margins, often necessitating repeated surveillance and imposing both financial and psychological burdens on patients. To address this limitation, we developed endoscopic muscularis superficialis dissection (EMSD), a technique involving controlled dissection into the superficial muscularis propria layer to improve complete resection rates. This study aimed to compare the therapeutic outcomes of EMSD and ESD for small rNETs. Methods This retrospective study enrolled 82 patients (88 rNETs) undergoing ESD or EMSD between May 2019 and June 2025. Primary outcomes included complete resection rates, complication rates, and postoperative hospital stay. Results The study analyzed 35 lesions treated with EMSD and 53 with ESD. Both groups had similar tumor characteristics. Compared to ESD, EMSD achieved significantly higher rates of both complete vertical margin resection (100% vs. 69.8%, p < 0.001) and R0 resection (100% vs. 67.9%, p < 0.001). However, there were no significant differences in procedure time (47.0 ± 17.0 min vs. 40.0 ± 9.5 min; p = 0.070) and postoperative hospital stay (4.0 ± 1.5 days vs. 4.0 ± 1.0 days; p = 0.676). Postoperative bleeding occurred in 1 EMSD patient (2.9%), which was managed endoscopically. No other bleeding or perforation cases occurred. Conclusions Compared with ESD, EMSD achieved superior performance in the resection of rNENs ≤ 10 mm in diameter regardless of submucosal invasion depth.