P0930 Cumulative Local and Metachronous Recurrence Rates After Endoscopic Submucosal Dissection of Ulcerative Colitis-Associated Neoplasia

Abstract Background Endoscopic submucosal dissection (ESD) is considered a less invasive and curative alternative for ulcerative colitis-associated neoplasia (UCAN), especially when endoscopic mucosal resection is not feasible to achieve complete resection1. The recent adoption of ESD as a curative alternative to total proctocolectomy (TPC) for UCAN has created a specific patient subgroup that is not covered by the current surveillance guidelines2-4. We therefore investigated the cumulative incidences of local and metachronous recurrence after ESD for suspected or confirmed UCAN to provide evidence for optimal post-ESD surveillance strategies. Methods We retrospectively reviewed 55 patients diagnosed with established or suspected UCAN between August 2009 and August 2025 at Asan Medical Center. Patients were classified as colectomy or ESD candidates based on endoscopic resectability. The primary outcome was the cumulative incidence of local and metachronous recurrence of dysplasia after ESD. Results ESD was performed for 45 lesions in 44 patients (Figure 1). En bloc and R0 resection rates were 91.1% and 82.2%, respectively, with no perforations. After ESD, 5 patients underwent colectomy without surveillance owing to missed synchronous adenocarcinoma (n = 2), remnant high-grade dysplasia (n = 1), multiple synchronous low-grade dysplasias (n = 1), and deep submucosal invasive cancer identified in the ESD specimen (n = 1). The remaining 39 underwent post-ESD surveillance, 37 with high-definition dye chromoendoscopy and two with narrow-band imaging. During a median follow-up of 36 months, local recurrence occurred in three patients: two were treated endoscopically, but the other required colectomy. The cumulative incidence of local recurrence reached 7.8% at 8.3 months, with no further cases thereafter. The cumulative incidence of metachronous recurrence was 36.4% at 45.2 months (Figure 2). Among eleven patients with metachronous dysplasia, six were treated endoscopically and two underwent colectomy; one died of non-colorectal cancer-related causes, while two others with untreated dysplasia due to poor performance status remained alive without progression to invasive cancer for 57.1 and 38.3 months. Conclusion ESD is a safe, and curative alternative to surgery for selected UCANs. However, because local and metachronous recurrences occur frequently within the first year, surveillance colonoscopy should be performed twice at 6-month intervals during the first year after ESD, followed by annual colonoscopy if no local recurrence is detected. References: 1. Zeng QS, Zhao ZJ, Nie J, et al. Efficacy and Safety of Endoscopic Submucosal Dissection for Dysplasia in Ulcerative Colitis Patients: A Systematic Review and Meta-Analysis. Gastroenterol Res Pract. 2022;2022:9556161. Published 2022 Jan 25. doi:10.1155/2022/9556161 2. Murthy SK, Feuerstein JD, Nguyen GC, Velayos FS. AGA Clinical Practice Update on Endoscopic Surveillance and Management of Colorectal Dysplasia in Inflammatory Bowel Diseases: Expert Review. Gastroenterology. 2021;161(3):1043-1051.e4. doi:10.1053/j.gastro.2021.05.063 3. Gordon H, Biancone L, Fiorino G, et al. ECCO Guidelines on Inflammatory Bowel Disease and Malignancies. J Crohns Colitis. 2023;17(6):827-854. doi:10.1093/ecco-jcc/jjac187 4. East JE, Gordon M, Nigam GB, et al. British Society of Gastroenterology guidelines on colorectal surveillance in inflammatory bowel disease. Gut. Published online April 30, 2025. doi:10.1136/gutjnl-2025-335023 Conflict of interest: Seol, Hyunho: No conflict of interest Kim, Min Kyu: No conflict of interest Hong, Seung Wook: No conflict of interest Hwang, Sung Wook: No conflict of interest Park, Sang Hyoung: No conflict of interest Ye, Byong Duk: No conflict of interest Byeon, Jeong-Sik: No conflict of interest Myung, Seung-Jae: No conflict of interest Kim, Jihun: No conflict of interest Kim, Sehee: No conflict of interest Yang, Suk-Kyun: No conflict of interest Yang, Dong-Hoon: No conflict of interest