Efficacy of endoscopic intermuscular dissection vs. endoscopic submucosal dissection in treating rectal neuroendocrine tumors < 10 mm.

Background and study aims: Rectal neuroendocrine tumors (r-NETs) exhibit significant heterogeneity and malignant potential. Currently, endoscopic resection is the preferred treatment for r-NETs < 10 mm. However, traditional endoscopic resection carries a risk of positive vertical margins. This study aimed to compare clinical efficacy of endoscopic intermuscular dissection (EID) and endoscopic submucosal dissection (ESD) in treating small r-NETs (< 10 mm).

Patients and methods: This retrospective study included 56 patients with r-NETs < 10 mm who underwent endoscopic treatment between April 2017 and September 2024 at Shenzhen University Affiliated South China Hospital and Shenzhen Hospital of Southern Medical University. All procedures were performed by the same surgeon. Patients were divided into two groups based on type of endoscopic treatment: the EID group (n = 16) and the ESD group (n = 40). We compared operative time, technical success rates, resection outcomes, adverse event (AE) rates, and histopathological findings between the two groups.

Results: Median lesion size in the EID group (7.5 mm) was significantly larger than in the ESD group (6.0 mm) ( P = 0.001). Although operative time in the EID group was longer (39 vs 28.5 minutes), the difference was not statistically significant ( P = 0.137). The complete resection rate was 100% in the EID group and 97.5% in the ESD group, with no statistically significant difference. There were no significant differences in general characteristics, technical success rates (100% vs 100%), or incidence of AEs (bleeding, perforation, infection) (0% vs 0%) between groups ( P > 0.05).

Conclusions: Endoscopic intermuscular dissection offers a better option for preventing positive basal margins and demonstrates good safety and feasibility.