Safety and efficacy of margin and base ablation after endoscopic mucosal resection of large nonpedunculated colorectal polyps: a prospective multicenter study

Background and Aims: EMR is the mainstay of therapy for large colorectal polyps. A previous study has shown low adverse events and recurrence rates after EMR with margin and selective base ablation using hybrid argon plasma coagulation. We were interested in evaluating the safety and efficacy of EMR with systematic margin, complete base, and vessel ablation in a multicenter prospective setting. Methods: Adults (18-89 years) undergoing EMR of nonpedunculated colorectal polyps ≥20 mm were enrolled consecutively in a prospective multicenter study. Patients received, after EMR completion, systematic ablation of the postresection margin, the complete base, and any visible vessels, without defect clipping. The co-primary outcomes were adverse events within 30 days, including severe postendoscopic bleeding, defined as requiring hospitalization, transfusion, colonoscopy, or surgery, and the proportion of local recurrence at the first surveillance colonoscopy (SC1), based on image-enhanced endoscopy and biopsies of the scar and on histology of resected visible recurrences. Results: One hundred sixty-four patients with 179 EMRs were included and completed SC1. Base ablation was performed in 167 (93.3%), and vessels were present and ablated in 116 (64.8%). Severe postendoscopic bleeding occurred in 2.2% (95% CI, 0.6-5.6), all in proximal polyps that were not clipped. Postprocedural perforation occurred in 0.6% (95% CI, 0.0-3.1), and postpolypectomy syndrome occurred in 1.7% (95% CI, 0.3-4.8). At SC1, performed at median 5.5 months, all 179 polyp sites were identified, and the proportion of local recurrence was 2.2% (95% CI, 0.6-5.6). Conclusions: In a prospective multicenter study, EMR with systematic ablation of the complete postresection base and visible vessels in addition to margin ablation demonstrated high technical success, low adverse events, and low recurrences. A randomized controlled trial is needed to compare the safety and efficacy of systematic base and margin ablation to margin ablation only.