STSC-HybridAPC Trial

Snare Tip Soft Coagulation Versus Hybrid APC (ERBE) for Post-EMR Margin Thermal Ablation - A Prospective Randomized Controlled Trial

Margin thermal ablation after piecemeal EMR significantly reduces recurrence of large colorectal polyps. As recurrence rates are now low, the key implementation question relates to efficiency and reproducibility of different ablation techniques. This randomized controlled trial compares snare tip soft coagulation (STSC) with Hybrid APC (ERBE), with procedural time as the primary endpoint.

Piecemeal endoscopic mucosal resection (EMR) of large (≥20 mm) non-pedunculated colorectal lesions was historically associated with local recurrence rates in the range of 15-20% at first surveillance when no systematic margin therapy was applied¹. The introduction of structured post-EMR margin thermal ablation has substantially altered this landscape. In a landmark randomized controlled trial, systematic thermal ablation of the resection margin reduced recurrence from 21% to 5%². Subsequent prospective and multicenter studies performed in high-volume expert centers using standardized circumferential snare-tip soft coagulation (STSC) protocols have demonstrated further reductions, with reported recurrence rates approaching 1-2%³. Most recently, Gauci et al. demonstrated that complete margin thermal ablation eliminates lesion size as a risk factor for recurrence following piecemeal EMR of large non-pedunculated colorectal polyps, reinforcing the durability and consistency of this approach in contemporary practice⁴. These findings are supported by meta-analytic data confirming that thermal margin ablation significantly reduces recurrence compared with no ablation without increasing clinically meaningful adverse events⁵. Accordingly, current international guidelines strongly recommend routine thermal ablation of the post-EMR mucosal defect margin following piecemeal resection of large colorectal lesions⁶.

Given that recurrence rates are now low when complete circumferential ablation is systematically performed, additional trials powered for recurrence would require prohibitively large sample sizes to detect incremental differences. The remaining clinically relevant gap therefore relates not to efficacy, but to procedural efficiency, reproducibility, and implementation, particularly in early-career or non-advanced interventional endoscopists.

Snare-tip soft coagulation requires precise contact-based application of thermal energy at each point sequentially along the entire resection margin, demanding consistent tip positioning and repeated fine manipulations. This technical precision may be particularly challenging for endoscopists with limited experience, increasing the risk of incomplete ablation or prolonged procedural time.

Hybrid APC (ERBE) delivers thermal energy via a non-contact argon plasma beam with a broader coagulation footprint per activation, potentially enabling faster and more reproducible circumferential coverage with fewer individual applications. The wider energy spread of Hybrid APC may therefore reduce operator-dependent variability and facilitate more consistent margin treatment, particularly in the hands of early-career endoscopists. Whether this translates into a meaningful reduction in net ablation time and improved completion rates compared with STSC has not been prospectively evaluated.

Inclusion Criteria:

• Age ≥18 years
• Undergoing piecemeal EMR of a non-pedunculated colorectal lesion ≥20 mm in size
• Macroscopically complete resection achieved prior to margin ablation (no visible residual adenomatous tissue at the resection base)
• Ability to provide written informed consent

Exclusion Criteria:

• Lesions requiring en bloc resection by ESD
• Lesions with suspected deep submucosal invasion based on endoscopic assessment (e.g., depressed morphology, non-lifting sign, NICE type 3 pattern, or equivalent advanced imaging criteria)
• Inflammatory bowel disease with active colitis at the lesion site
• Overt invasive carcinoma requiring surgical management
• Pregnancy
• Inability to provide informed consent