Background and aims: Endoscopic mucosal resection (EMR) is standard of care for the management of large (≥20mm) non-pedunculated colonic polyps (LNPCPs). Its efficacy and cost effectiveness were limited by recurrence. Margin thermal ablation (MTA) to the post-EMR defect, has greatly mitigated this problem. However, electrocautery-related complications of delayed bleeding and perforation incur significant morbidity.
Cold snare polypectomy is effective and safe for the resection of small polyps with negligible recurrence rates. Application of cold snare resection to LNPCPs, while an attractive alternative, lacks high-quality evidence. We conducted a randomized trial to compare the efficacy and safety of cold EMR (C-EMR) to conventional (H-EMR).

Methods: A prospective single-centre randomized controlled trial was conducted at an Australian tertiary referral centre for flat, 15-50mm adenomatous LNPCPs referred for endoscopic resection. Prior to resection, eligible LNPCPs were randomly assigned to EMR using a dedicated cold snare or conventional H-EMR with margin thermal ablation (control). First surveillance colonoscopy (SC1) was conducted 6 months following resection. Scars were evaluated with high-definition white-light, narrow-band imaging and biopsy. The primary outcome was endoscopically visible and/or histologically confirmed recurrence at SC1. Secondary outcomes were clinically significant post-EMR bleeding (CSPEB), delayed perforation and technical success.

Results: 931 LNPCPs were referred for endoscopic resection between November 2019-September 2023. 180 LNPCPs in 177 patients met eligibility criteria and were randomized to either the C-EMR arm (n=87) or H-EMR arm (n=93). Treatment groups were equivalent (Table 1) with no significant difference in lesion size or technical success (86/87 (98.9%) vs 93/93 (100%); p=0.3). One C-EMR required conversion to H-EMR due to unexpected submucosal fibrosis. Following exclusions (Figure 1), 129 LNPCPs undertook SC1 (68 C-EMR, 61 H-EMR). 39 patients await surveillance. On intention to treat and per protocol analysis, recurrence was significantly greater in C-EMR (15/87, 17.2% vs 1/93, 1.1%; p<0.001 and 15/68, 22.1% vs 1/61, 1.6%; p<0.001 respectively). Significant deep mural injury (24/93 (25.8%) vs 0; p<0.001) and delayed perforation (1/93 (1.1%) vs 0; p=0.33) only occurred in the H-EMR group. CSPEB and intraprocedural bleeding were significantly greater in the H-EMR arm (7/93 (7.5%) vs 1/87 (1.1%); p = 0.038 and 10/93 (10.8%) vs 0/87 (0%); p=0.002 respectively).

Conclusion: Compared to conventional H-EMR, C-EMR for flat, adenomatous LNPCPs, demonstrates superior safety with equivalent technical success. However, endoscopic recurrence is significantly greater for cold snare resection and is currently a limitation of the technique.

Arnout Van Hattem

Appearances