The Effectiveness and Safety of Endoscopic Intermuscular Dissection for the Treatment of Rectal Gastrointestinal Stromal Tumors: A Pilot Feasibility Study.

Background/Objectives: Rectal gastrointestinal stromal tumors (GISTs) near the dentate line (DL) present significant surgical challenges due to anatomical constraints and difficulty preserving anal function. Endoscopic intermuscular dissection (EID) is a viable alternative in these cases. Methods: We retrospectively reviewed the medical records of patients who underwent EIDs for rectal GISTs near the DL between January 2015 and December 2023. The primary outcomes assessed were procedural efficacy-measured by en bloc and complete resection rates-and safety, evaluated regarding delayed bleeding, perforation, and tumor recurrence. Results: In total, 10 patients underwent rectal GIST EIDs. The mean tumor size, procedure time, and resection speed were 25.70 ± 14.09 mm, 81.30 ± 46.20 min, and 16.91 ± 9.94 mm2/min, respectively. The en bloc and complete resection rates were 100% and 70%, respectively. Compared with endoscopic submucosal dissection (ESD) for rectal epithelial lesions, there were no significant differences in procedure times (81.30 ± 46.20 min vs. 76.50 ± 32.42 min, p = 0.758) or complete resection rates (70% vs. 95%, p = 0.095). Regarding safety, delayed bleeding (10% vs. 10%, p = 1.000) and perforation (10% vs. 0%, p = 0.333) rates did not differ significantly between the two groups. During a median 36-month follow-up, one recurrence occurred in a patient with a high-risk GIST. Conclusions: EID for rectal GISTs near the DL appears to be a feasible and potentially safe treatment option in carefully selected patients. It may represent a less invasive alternative to surgery, particularly when preservation of anal function is a priority. Nevertheless, validation in larger prospective studies is required.