We read with interest the article by Ito et al. [1] on the resection depth and layer of cold snare polypectomy (CSP) versus endoscopic mucosal resection (EMR). They clarified histopathological features of CSP specimens compared with EMR specimens. Among 193 completely resected specimens, the median resection depth from the muscularis mucosae in CSP vs. EMR was 76 vs. 338 μm (p < 0.001), and resection layer was the submucosa in 7/79 (9%) vs. 105/114 (92%) (p < 0.001). Although they concluded that CSP was a significant risk factor for unevaluable/positive vertical margin, we believe that the resection depth measurement would be meaningless for mucosal lesions in EMR specimens.

The incidence and mortality of colorectal cancer (CRC) have been rising. CRC is a common cause of cancer-related deaths worldwide [2]. Significant efforts have been made to reduce the incidence and mortality of CRC [3]. Since colorectal polyps have a risk of advanced neoplasia and malignancy, endoscopic removal reduces the incidence and mortality of CRC [1,2,3,4]. Polypectomy (cold or hot) and EMR have been widely used for colorectal polyp removal [1, 2].

Recently, CSP is frequently used for removal of small colorectal polyps, and is a safe and easy technique because of a low risk of adverse events, such as bleeding and perforation, as well as a short procedure time [1,2,3]. The resection depth achieved by CSP is significantly more superficial than that achieved by hot snare polypectomy [2]. Although CSP requires no submucosal fluid injection or electrocautery, EMR requires adequate mucosal lift by submucosal fluid injection for definite en bloc resection and prevention of perforation [1,2,3].

Due to the submucosa expanded by fluid injection in EMR, the resection depth of EMR specimens (the “false” submucosa) is deeper than that of CSP specimens (the “true” submucosa). Although the submucosal invasion depth is not changed by fluid injection in submucosal cancers [5], we believe that the resection depth comparison between the “false” submucosa in EMR and the “true” submucosa in CSP would be meaningless in mucosal lesions.