Post written by Yohei Yabuuchi, MD, and Kenichiro Imai, MD, from the Division of Endoscopy, Shizuoka Cancer Center, Shizuoka, Japan.
Recently, cold-snare endoscopic mucosal resection (EMR), which combines submucosal injection and cold-snare polypectomy, has been adapted in a piecemeal fashion as a safe and effective procedure for colorectal polyps of 10 mm or more. However, piecemeal resection requires surveillance colonoscopy at shorter intervals. If cold-snare EMR can achieve en bloc complete resection, similarly to hotsnare polypectomy, cold-snare EMR can be a promising option with extreme safety and without increasing the burden of surveillance colonoscopy. We focused on en bloc cold-snare EMR to adapt the resection technique without electorocautery for 10–14 mm adenomas.
This prospective observational study demonstrated that cold-snare EMR for 10–14 mm colorectal adenomas was safe and effective with no severe adverse events and a 63.8% histological complete resection rate. A major reason for unsuccessful histological complete resection was inability to cut without electrocautery in 13.7% of cases. In our analysis, the use of a 15-mm snare was associated with failure of cold-snare EMR. Capturing a large amount of tissue to attempt en bloc removal may lead to resection failure, which is a possible limitation of en bloc cold-snare EMR.
This study provided 3 findings on the effects of submucosal injection and electrocautery. First, submucosal injection has no adverse effects because major adverse events such as delayed bleeding and perforation did not occur in this study. Second, submucosal injection may assure horizontal margins for polyps sized 10–14 mm. The reported incomplete resection rates by CSP for subcentimetric polyps ranged from 1.8% to 3.9%, which was comparable to that of 4.3% in cold-snare EMR for 10–14 mm polyps when achieving resection without electrocautery. Third, cold-snare EMR may cut above the submucosal layer, similar to CSP. The reported rates of specimens containing submucosal tissue for CSP, HSP, and hot-snare EMR were 8.9–24.0%, 81.5%, and 92.1%, respectively. Submucosal tissues were found in 14.5% of cold-snare EMR, comparable to CSP, indicating that removal of submucosal tissues requires electrocautery rather than submucosal injection. Recent prospective studies reported that white protrusions, which occurred in 14-34% of CSP, pathologically included the muscularis mucosa and submucosa in 76-80% and 90%, respectively. In this study, white protrusions were observed in 60.9% of cold-snare EMR cases, while all specimens resected by cold-snare EMR included the muscularis mucosa. These findings indicated that the cutting level of cold-snare EMR may involve the muscularis mucosa although the epithelium and lamina propria were completely removed by cold-snare EMR.
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