Current status and future perspectives of submucosal endoscopic surgeries for esophageal benign diseases

[Aims] The success of POEM procedure has opened a new door of endoscopic treatments, from the mucosal layer to the deeper submucosal space. Based on these experiences, we have developed several submucosal endoscopic treatments. Our aim is to introduce these procedures and show their clinical results. [Methods] The clinical outcomes were analyzed in these 4 submucosal endoscopic treatments: POEM, per-oral endoscopic tumor resection (POET) for submucosal tumors, endoscopic diverticulum resection for Zenker’s or epiphrenic diverticulum, and per-oral endoscopic fundoplication (POEF) for GERD. [Results] By the end of 2020, we performed 2352 cases of POEM, 54 of POET, 2 of diverticulum resection, and 46 of POEF. A response rate of POEM was 95.0% and symptomatic post-POEM GERD was 14.7%. A procedural completion rate of POET was 92.6%. For Zenker’s diverticulum, submucosal endoscopic septectomy was done, and for epiphrenic diverticulum, endoscopic suturing closure of the muscular defect at diverticulum and removal of inverted diverticulum mucosa was performed. Both were successfully done. POEF procedure is an endoscopic fundoplication following POEM procedure. The endoscope advanced into the abdominal cavity from the distal end of the submucosal tunnel, and partial fundoplication was made by retracting the anterior gastric wall at the esophagogastric junction. POEF was technically feasible. [Conclusion] These techniques of submucosal endoscopic treatments have been proven safe and promising, and may evolve minimally invasive surgeries in the future