Poster Session I - A175 COMPARATIVE ANALYSIS OF RESIDUAL NEOPLASIA AND PROCEDURAL OUTCOMES IN CURATIVE VERSUS NON-CURATIVE COLORECTAL ENDOSCOPIC SUBMUCOSAL DISSECTION

Abstract Background Endoscopic submucosal dissection (ESD) achieves en bloc removal of colorectal neoplasia. Resections with positive margins, lymphovascular invasion (LVI), or deep submucosal invasion (SMI) are considered non-curative, though margin positivity alone may rarely cause recurrence in non-invasive disease. Aims To compare baseline, procedural, and pathological characteristics of curative versus non-curative colorectal ESD in a Western tertiary center, and describe management and outcomes of R1 resections. Methods We retrospectively analyzed colorectal ESDs (July 2016-Dec 2022). Cases were classified as curative or non-curative per standard pathological criteria. Baseline, procedural, and histologic variables were compared; R1 resections were reviewed for management and outcomes. Results We analyzed 192 ESDs (158 curative, 34 non-curative; colon 100, rectum 92); median age 70.5 years (36–94). Most lesions were JNET 2B (82.6%). Groups did not differ by age, lesion size, or LST type. Non-curative resections were more often rectal (60.0% vs 44.3%, p = 0.038), JNET 3 (27.3% vs 0.6%, p < 0.001), and had previously been biopsied (70.6% vs 49.4%, p = 0.036). No significant between-group differences were observed in procedural metrics, en bloc resection (98.7% vs 97.1%, p = 0.445), or adverse events (3.1% vs 0%, p = 1.00). Pathology diverged: R0 was less frequent in non-curative cases (55.9% vs 96.8%, p < 0.001), adenocarcinoma was more common (64.7% vs 25.0%), and HGD less common (20.6% vs 58.2%) (both p < 0.001). Of the 34 non-curative cases, 6 proceeded to surgery with no residual disease. Fourteen were followed with surveillance (median 12 months, range 3-43) without clinical or endoscopic recurrence; 2 died of other causes before follow-up, and the remaining 12 were either awaiting follow-up or managed by their referring service. Conclusions In this series, non-curative classification was driven by adverse histology and deep invasion rather than technical performance. The small number of true R1 resections and limited follow-up precluded disease-free survival analysis, but the absence of observed recurrence supports consideration of close surveillance in carefully selected non-curative cases after multidisciplinary review and shared decision-making Funding Agencies None