P3658 - Safety and Efficacy of Underwater Endoscopic Mucosal Resection of Colorectal Polyps and Risk of Recurrence: A large multi-year series

Frances Dang, MD¹, Amirali Tavangar, MD¹, Michael Andrew Yu, MD¹, Andy L. Lin, MD¹, Trevor McCracken, MD², Shoujit Banerjee, MD², Joshua Kwon, MD², Avni Jain, MD³, David L. Cheung, MD¹, Monica Mullin, MD⁴, Thinh Pham, BSc², John G. Lee, MD¹, Jason Samarasena, MD^1
1University of California, Irvine, Orange, CA; ²University of California Irvine, Orange, CA; ³University of California Irvine Digestive Health Institute, Orange, CA; ⁴University College London Hospitals, London, England, United Kingdom

Introduction:




Endoscopic resection of colorectal polyps reduces cancer related mortality, with incomplete polypectomy has been identified as an important cause of interval cancer. Endoscopic mucosal resection (EMR) is the standard treatment for non-pedunculated colorectal polyps. Underwater EMR (UEMR) is a technical variant that does not involve injection of fluid into the submucosa and relies on submerging the polyp in water before hot snare resection.










Methods: This is a single center retrospective study of all adult patients ( >18 years old) that underwent UWEMR of colonic polyps at the University of California Irvine from January 2018 to January 2024. The primary outcome was polyp recurrence at surveillance colonoscopy. Secondary outcomes included technical success, polyp pathology, en-bloc resection rate, margin ablation technique and adverse events. Descriptive characteristics were calculated for variables of interest and a regression analysis of factors associated with polyp recurrence were conducted.












Results:




In the study period, a total of 526 patients were identified with resection of 626 polyps by UEMR technique. The mean age of patient was 64 years, with 50% male. For our primary outcome, recurrence identified on first surveillance colonoscopy was 9% (60/617). On logistic regression, polyp size and piecemeal resection was significantly associated with higher recurrence while fellow participation was associated with less recurrence (See Table 1). Mean polyp size was 22.5 mm (Range 12-80mm, SD 12mm). Polyp pathology was tubular adenoma in 32.7%, tubulovillous adenoma 23.3%, serrated adenoma 19.8% , high grade dysplasia 8.13% and adenocarcinoma 5.04%. Technical success was achieved in 98% (614/626). En bloc resection was achieved in 46% (289/626). Margin ablation with STSC or APC occurred in 42.1% (264/626) of polyps resected. The adverse event rate was 6% (38/625) with major bleeding in 3.2% (17/625) and perforation requiring surgical intervention in 0.16% (1/625) of patients. The mean follow-up time to first surveillance colonoscopy was 206 days.










Discussion:




In this very large, real-world, single center 6-year experience of patients who underwent UEMR for resection of non-pedunculated polyps, UEMR demonstrated a low recurrence rate, low adverse event rate and high technical success. These results are consistent with smaller prospective trials using this technique. Underwater EMR should be considered a safe alternative to conventional EMR at this time.


Disclosures:


Frances Dang, MD¹, Amirali Tavangar, MD¹, Michael Andrew Yu, MD¹, Andy L. Lin, MD¹, Trevor McCracken, MD², Shoujit Banerjee, MD², Joshua Kwon, MD², Avni Jain, MD³, David L. Cheung, MD¹, Monica Mullin, MD⁴, Thinh Pham, BSc², John G. Lee, MD¹, Jason Samarasena, MD¹. P3658 - Safety and Efficacy of Underwater Endoscopic Mucosal Resection of Colorectal Polyps and Risk of Recurrence: A large multi-year series, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.