The goal of this clinical trial is to clarify the role of adjuvant thermal ablation for non-thermal endoscopic mucosal resection (EMR) of large (≥20mm) flat colorectal polyps (so-called laterally spreading lesions \[LSLs\]).
The hypothesis is that adding adjuvant thermal ablation to non-thermal EMR (vs no ablation) will result in lower lesion recurrence rates at 6-month follow-up, and non-inferior adverse events (AE) rates 14 days post EMR.
For participants with planned EMR, endoscopists will perform non-thermal EMRs as per standard of care and:
* adjuvant thermal ablation will either not be performed (control group), or will be applied to the base and outside margins of the resection site (experimental group);
* then, all patients will be contacted 14-44 days after EMR, to verbally ascertain the occurrence of AEs;
* then, all patients will undergo a first follow-up colonoscopy at 6 months after initial conoloscopy to assess lesion recurrence;
* finally, all patients will undergo a second and final colonoscopy 18 months after EMR.