Endoscopic intermuscular dissection and endoscopic submucosal dissection for treatment of rectal neuroendocrine tumors: a retrospective cohort study

BACKGROUND: The incidence of rectal neuroendocrine tumors (rNETs) is increasing due to widespread colonoscopy screening. Conventional endoscopic techniques have difficulties in achieving complete resection of rNETs with deep submucosal invasion. Endoscopic intermuscular dissection (EID) enables removal of the mucosa, submucosa, and inner circular muscle layer while preserving rectal wall integrity. METHODS: We retrospectively analyzed the patients diagnosed with rNETs between May 2022 and May 2025 at our hospital. Clinical data, endoscopic findings, histopathological results, and follow-up outcomes were reviewed. RESULTS: A total of 13 patients underwent EID for rNETs were enrolled, with 13 ESD cases included for paired comparison. Both groups demonstrated sufficient histologically complete resection rates (92.3% vs 100%, p>0.99). EID required longer procedure time (38.31 ± 12.84 vs. 29.54 ± 4.75 min, p=0.036). Hospitalization costs showed no significant difference (14795.92 ± 2946.61 vs. 12363.00 ± 2585.15, p=0.105).1 case of delayed bleeding occurred in each group, respectively, with no other serious adverse events. No recurrence was reported in 25 cases that achieved histologically complete resection. CONCLUSIONS: EID is safe and effective for rNET resection without increasing costs compared to ESD. It may be a feasible option for selected rNETs with suspected deep submucosal invasion requiring adequate vertical margins.