POEM and Submucosal Tunneling.

Submucosal endoscopy has introduced new and important aspects into gastrointestinal endoscopic therapeutics by opening the way to interventions even outside of the GI tract. At present, innovative techniques for submucosal endoscopy in different esophageal diseases include peroral endoscopic myotomy (POEM) for idiopathic achalasia and related motility disorders, submucosal tunneling endoscopic resection (STER) for submucosal tumors arising from the muscularis propria, and endoscopic submucosal tunneling dissection (ESTD) for superficial esophageal neoplastic lesions. POEM for achalasia-still a rare disease-is currently evaluated in comparison to endoscopic and surgical standard therapies, while this procedure enabling a long thoracic myotomy might constitute an advantage over the laparoscopic approach in treatments of spastic esophageal diseases. Removal of smaller submucosal esophageal tumors may appear tempting, but the clinical indications are limited by the facts that the vast majority of such smaller tumors are asymptomatic and benign.For all these innovative and technically demanding techniques, learning curves have to be taken into account, not only with regard to technical competence but also to clinical assessment, ranging from proper indication and patient selection to the management of (potential) complications and logistics/back-up. Although preliminary results from high-skilled endoscopic centers have been very encouraging, long-term data as well as prospective randomized controlled trials are needed to validate the efficacy and safety of the modalities.