Safety and Efficacy of Endoscopic Mucosal Resection of Large Nonpedunculated Colorectal Polyps with Margin, Base and Vessel Ablation: A Prospective Multi-Center Study

Aims Endoscopic mucosal resection (EMR) is the mainstay of therapy for large colorectal polyps. A previous study from our group has shown low adverse events and low recurrence rates after EMR with margin and selective base ablation using hybrid argon plasma coagulation (hAPC) [1]. We were interested in evaluating, in a second study phase, the safety and efficacy of EMR with systematic margin, complete base and vessel ablation using hAPC in a multicenter prospective setting and to evaluate combined outcomes over these two study phases.

Methods Adults (18–89 years) undergoing EMR of nonpedunculated colorectal polyps≥20mm were enrolled consecutively in a prospective multicenter study from 2019 to 2024 in Canada (University of Montreal, University of Toronto, University of British Columbia) and the United States (Penn State College of Medicine). In the first study phase, patients received margin ablation using hybrid argon plasma (hAPC) after EMR, with additional therapies at the discretion of the endoscopist including selective base ablation, defect clipping and/or prophylactic treatment of visible vessels. In the second study phase, patients received, after EMR completion, systematic ablation of the post-resection margin, the complete base and any visible vessels using hAPC, with vessel ablation as the primary prophylactic therapy for bleeding. The co-primary outcomes were adverse events within 30 days, including severe post-endoscopic bleeding, and the proportion of local recurrence at the first surveillance colonoscopy (SC1), based on image-enhanced endoscopy and biopsies of the scar and based on histology of resected visible recurrences.

Results A total of 239 patients (mean age 66.5 years, 46.4% female) were included and underwent 269 EMRs (mean polyp size 34.4 mm, 78.4% proximal to the splenic flexure, 96.3% piecemeal resections). Epinephrine was injected and/or used in the hAPC solution in 98.9%. Margin ablation was performed in all cases, and partial or complete base ablation was performed in 229 cases (85.1%). Prophylactic therapy of visible vessels was performed in 141 cases (52.4%) using hAPC ablation of visible vessels for the majority (108/141, 76.6%). Defect clipping was performed in 56 cases (20.8%). Severe post-endoscopic bleeding occurred in 2.2% [95% CI, 0.8-4.8] (6/269). Non-severe post-endoscopic bleeding occurred in 4.5% [95% CI, 2.3-7.7] (12/269). Post-procedural perforation occurred in 0.7% [95% CI, 0.1-2.7] (2/269). At SC1, performed at a median of 5.8 months, the overall local recurrence rate was 2.2% [95% CI, 0.8-4.8] (6/269).

Conclusions In a prospective multicenter study, EMR with selective or complete hAPC ablation of the resection base and visible vessels in addition to margin ablation demonstrated high technical success, low adverse events and low recurrences. A randomized controlled trial is ongoing to compare the safety and efficacy of base and margin ablation to margin ablation only.

Publikationsverlauf

Artikel online veröffentlicht:
27. März 2025

• References

• 1 Motchum L, Levenick JM, Djinbachian R. et al. EMR combined with hybrid argon plasma coagulation to prevent recurrence of large nonpedunculated colorectal polyps (with videos). Gastrointest Endosc 2022; 96 (05): 840-848.e2