Impact of margin thermal ablation after cold-forceps avulsion with snare-tip soft coagulation for nonlifting large nonpedunculated colorectal polyps

Background: Nonlifting large nonpedunculated colorectal polyps (NL-LNPCPs) account for 15% of LNPCPs and are effectively managed by endoscopic mucosal resection (EMR) with adjunctive cold-forceps avulsion with adjuvant snare-tip soft coagulation (CAST). Recurrence rates >10% at surveillance colonoscopy are however a significant limitation. We aimed to compare the outcomes of CAST plus margin thermal ablation (MTA) versus CAST alone for NL-LNPCPs. Methods: Prospective observational data on consecutive patients with NL-LNPCPs treated by EMR and CAST at a single tertiary center were retrospectively evaluated. Two cohorts were established: the pre-MTA period (January 2012–June 2017) and the MTA period (July 2017–October 2023). The primary outcome was the residual/recurrent adenoma (RRA) rate at first surveillance colonoscopy (SC1). Secondary outcomes included the RRA rate at SC2 and adverse events. Results: Over 142 months, 300 patients underwent EMR and CAST for LNPCP: 103 lesions pre-MTA and 197 with MTA. At SC1 and SC2, recurrence was lower in the MTA cohort compared with the pre-MTA cohort (5.0% vs. 18.8% and 0.8% vs. 10.0%, respectively; both P<0.001). Adverse events were similar between the two cohorts for deep mural injury types III–V (pre-MTA 2.9% vs. MTA 5.6%; P=0.29) and delayed bleeding (pre-MTA 8.7% vs. MTA 7.1%; P=0.49). On multivariate analysis, MTA was the only variable independently associated with a reduced likelihood of recurrence (odds ratio 0.20, 95%CI 0.07–0.54; P=0.001). Conclusions: For NL-LNPCPs, MTA in combination with CAST is safe and effective and reduces recurrence at SC1 in comparison with CAST alone.