Clinical outcomes of endoscopic resection for rectal neuroendocrine tumors: Advantages of endoscopic submucosal resection with a ligation device compared to conventional EMR and ESD

Objectives: There are some endoscopic resection (ER) methods for neuroendocrine tumors (NETs), however, which method is most useful remains unclear. This study aimed to compare the outcomes of different ER techniques, such as conventional endoscopic mucosal resection (cEMR), endoscopic submucosal dissection (ESD), and endoscopic submucosal resection with a ligation device (ESMR-L) for rectal NETs. Methods: We retrospectively analyzed 96 consecutive patients with 102 rectal NETs of less than 10 mm in diameter who underwent ER between January 2001 and December 2019 at Hiroshima University Hospital. We compared the clinical outcomes of each ER method (cEMR 60 lesions, ESD 21 lesions, and ESMR-L 21 lesions), divided according to the treatment periods, and evaluated the risk factors for vertical margin (VM) positivity in relation to clinicopathological and endoscopic characteristics. Results: As for the mean procedure time, ESD took significantly longer to perform than the other methods. The histological complete resection rate was 80% (48/60) for cEMR, 85.7% (18/21) for ESD, and 100% (21/21) for ESMR-L, and the VM positive rate was 20% (12/60) for cEMR, 14.3% (3/21) for ESD, and 0% (0/21) for ESMR-L, with no significant difference. However, the tumor-front-to-VM distance was significantly longer in the ESMR-L group than in the cEMR and ESD groups. cEMR and ESD were both significant risk factors for VM positivity. No perforation or local recurrence was observed in all methods. Conclusions: ESMR-L is the most useful ER method for small rectal NETs.