Thermal ablation of resection margins has been shown to reduce recurrence after endoscopic mucosal resection (EMR) of large non-pedunculated colorectal polyps, however, to a variable extent. In addition, residual or recurrent adenoma (RRA) may also arise from remnants in the resection base. We present a combined technique of margin and base ablation using submucosal injection followed by low energy argon beamer coagulation: Of 113 cases treated this way, RRA was found in one case only (0.9%). These data from multicentre registries were significantly lower compared with cases with margin ablation only (n=170; RRA rate 8.8%) or cases without (n=144; RRA rate 23.4%) in the same databases. This difference persisted when analysing only large lesions ≥40 mm (2.4 vs 12.5 vs 28.1%; overall n=137). Bleeding and perforation rates were similar across all groups.

Significant efforts have been expended to reduce RRAs after EMR. Thermal margin ablation using snare tip soft coagulation (STSC) has recently emerged as a potential solution to the high RRAs with very low recurrence (<5%) observed in one group, but variable and less significant reductions (9%–13%) in other studies, limiting the generalisability of the results in the initial experience.1–5 Next to the margins the resection surface can be a potential nidus for recurrence, explaining the high recurrence rates especially found in >4 cm large non-pedunculated colonic polyps (LNPCPs) undergoing EMR with margin ablation.4 We hypothesised that double ablation (ablation of the margin and base) could potentially result in lower recurrence rates compared with single (margin only) ablation. We, therefore, compared recurrence rates after EMR with double, single and no ablation within prospectively collected data from three multicentred registries (NCT04220905, NCT04015765, NCT04117100).

EMR in all cases was performed according to current standards of care using piece-meal hot snare resection. In the single ablation group, cases that …