Endoscopic Resection of Rectal Neuroendocrine Tumors: How Deep Should We Go?

Background: Rectal neuroendocrine tumors (r-NETs) measuring 20 mm or less are increasingly diagnosed during colorectal cancer screening, but the optimal depth of endoscopic resection remains uncertain. Endoscopic submucosal dissection (ESD) is well established, whereas endoscopic intermuscular dissection (EID) may provide deeper resection for fibrotic or recurrent lesions. We hypothesized that EID would provide reliable deep-margin clearance without compromising safety. Methods: We retrospectively reviewed 42 consecutive patients treated at a tertiary center between 2018 and 2025. Thirty-two primary lesions underwent ESD and 10 lesions or scars suspicious for deep invasion underwent EID. Primary outcomes were en bloc and R0 resection; secondary outcomes were procedure time, adverse events, and length of stay. Groups were compared with the t, Mann-Whitney U, and chi-square tests. Results: En bloc resection was achieved in all cases. Histology confirmed R0 resection in all 26 primary lesions. Among 16 excision scars, 14 showed fibrosis only and 2 harbored grade 1 NET recurrence; both recurrent lesions were resected R0 with EID. Lesion size and procedure time were similar between groups. No major adverse events occurred. Self-limited intraprocedural bleeding occurred in five patients, and all patients were discharged within 2 postoperative days. Conclusions: Both techniques are safe and effective for r-NETs measuring 20 mm or less, and EID may be preferred for fibrotic or recurrent lesions. Large prospective multicentre studies are needed to validate the depth-tailored use of EID in r-NETs.