Outcomes of Thermal Ablation of the Mucosal Defect Margin After Endoscopic Mucosal Resection: A Prospective, International, Multicenter Trial of 1000 Large Nonpedunculated Colorectal Polyps.

Background & Aims Thermal ablation of the defect margin after endoscopic mucosal resection (EMR-T) for treating large (≥20 mm) nonpedunculated colorectal polyps (LNPCPs) has shown efficacy in a randomized trial, with a 4-fold reduction, in residual or recurrent adenoma (RRA) at first surveillance colonoscopy (SC1). The clinical effectiveness of this treatment, in the real world, remains unknown. Methods We sought to evaluate the effectiveness of EMR-T in an international multicenter prospective trial (NCT02957058). The primary endpoint was the frequency of RRA at SC1. Detailed demographic, procedural, and outcome data were recorded. Exclusion criteria were LNPCPs involving the ileo-caecal valve, the appendiceal orifice, and circumferential LNPCPs. Results During 51 months (May 2016–August 2020) 1049 LNPCPs in 1049 patients (median size, 35 mm; interquartile range, 25–45 mm; right colon location, 53.5%) were enrolled. Uniform completeness of EMR-T was achieved in 989 LNPCPs (95.4%). In this study, 755/803 (94.0%) eligible LNPCPs underwent SC1 (median time to SC1, 6 months; interquartile range, 5–7 months). For LNPCPs that underwent complete EMR-T, the frequency of RRA at SC1 was 1.4% (10/707). Conclusions In clinical practice, EMR-T is a simple, inexpensive, and highly effective auxiliary technique that is likely to significantly reduce RRA at first surveillance. It should be universally used for the management of LNPCPs after EMR. https://clinicaltrials.gov; Clinical Trial Number, NCT02957058.