Thermal ablation of the defect margin after endoscopic mucosal resection (EMR-T) for treating large (≥ 20mm) non-pedunculated colorectal polyps (LNPCPs) has shown efficacy in a randomized trial, with a four-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.