Clinical Outcomes of Margin Thermal Ablation After Piecemeal EMR and Predictors of Recurrence in Routine Practice: A Comparative Cohort Analysis

Aims Recurrence after piecemeal endoscopic mucosal resection (pEMR) of large nonpedunculated colonic polyps (LNPCPs) remains a major limitation of this technique. Margin thermal ablation (MTA) has been shown in randomized trials to reduce recurrence neoplasia, but evidence of its effectiveness and predictors of recurrence in routine clinical practice is still limited. This study evaluated the recurrence rates after pEMR of LNPCPs (≥20 mm) before and after implementation of MTA in a single high-volume endoscopy center. Secondary aims were to identify independent risk factors for local recurrence and to compare adverse events between two cohorts. Methods This single-center retrospective comparative cohort study included consecutive patients undergoing pEMR for LNPCPs≥20 mm during two time periods: 2013–2015 (without MTA) and 2022–2024 (with systematic MTA). Patients treated with standard pEMR without MTA between January 2013 and December 2015 were used as a historical control cohort, as complete endoscopic and surveillance data were available for this period and MTA had not yet been implemented in our unit. These outcomes were compared with a contemporary cohort of patients treated with pEMR and systematic MTA between 2022 and 2024. The primary endpoint was local recurrence at the first surveillance colonoscopy (SC1), performed 4–6 months after resection. Secondary outcomes included risk factors for recurrence and adverse event rates. Recurrence was defined as endoscopic and/or histological evidence of adenomatous tissue at SC1. All surveillance examinations were performed using high-definition white light and virtual chromoendoscopy. Results Data from 359 patients with 384 LNPCPs were analyzed. Of these, 232 LNPCPs were resected by pEMR. During 2013–2015, a total of 108 LNPCPs were treated with standard pEMR without MTA (S-pEMR), whereas during 2022–2024, 124 LNPCPs were resected with pEMR and systematic margin thermal ablation using snare-tip soft coagulation (T-pEMR). Baseline characteristics of patients undergoing SC1 were similar between groups. Local recurrence at SC1 was detected in 11 lesions (9%) in the T-pEMR group compared with 28 lesions (26%) in the S-pEMR group (p=0.0005; RR=0.34; 95% CI, 0.18–0.65). Local recurrence decreased by 17%, corresponding to a 66% relative risk reduction. Local recurrence was significantly associated with lesions≥30 mm (p=0.005) and high-grade dysplasia (p=0.005). Adverse events were comparable between groups, with no significant differences. Conclusions Margin thermal ablation following piecemeal EMR significantly reduced local recurrence in routine clinical practice, resulting in a 17% absolute and 66% relative reduction in recurrence without an increase in adverse events. High-grade dysplasia, and lesion size≥30 mm were independent predictors of recurrence. Recognition of these risk factors may help guide more tailored surveillance strategies. Supported by the Ministry of Health of the Czech Republic in cooperation with the Czech Health Research Council under project No.NU22-08-00424, educational projects DZRVO MO1012 and Cooperatio. Article published online: 05 June 2026 © 2026. European Society of Gastrointestinal Endoscopy. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany