Underwater Endoscopic Submucosal Dissection under General Anesthesia for Superficial Esophageal Carcinoma.

Background and study aims Conventional endoscopic submucosal dissection (C-ESD) for superficial esophageal carcinomas (SECs) can cause muscularis propria injury and post-ESD stenosis. Underwater ESD (U-ESD) facilitates muscle-sparing dissection but has been limited in the esophagus by aspiration concerns. This retrospective multicenter study evaluated the safety and effectiveness of esophageal U-ESD under general anesthesia. Patients and methods U-ESD under general anesthesia was selected for lesions ≥30 mm, ≥half circumferential involvement, post-treatment scarring, or aspiration/paradoxical agitation risk; other lesions underwent C-ESD. Primary outcome was muscularis propria exposure (MPE). Secondary outcomes were post-ESD stenosis, resection speed, en bloc/R0 resection, and adverse events. Given the predefined treatment allocation, outcomes were compared between groups on an exploratory analysis. Post-ESD stenosis was further analyzed according to MPE in the U-ESD group. Results Overall, 176 lesions were analyzed (U-ESD, 103; C-ESD, 73). The U-ESD group had larger lesions (45.2 vs. 22.1 mm) and more frequent ≥3/4 circumferential resection (70.8% vs. 6.8%). En bloc resection was achieved in all lesions; R0 resection rates were 96% and 94%, respectively. Resection speed was higher (15.2 vs. 7.6 mm 2 /min, p < 0.001) and MPE was less frequent (10.6% vs. 47.9%, p < 0.001) in the U-ESD group. Post-ESD stenosis was more frequent in the U-ESD group (11.6% vs. 1.3%, p = 0.015). Adverse events occurred only in the C-ESD group (4.1%). In the U-ESD group, post-ESD stenosis was more frequent with MPE than without MPE (45.4% vs. 7.6%, p = 0.001). Conclusion Esophageal U-ESD under general anesthesia appeared safe and efficient for large, technically demanding SECs, achieving both infrequent MPE and high resection speed.