Reply to Kanesaka et al.

There is persistent uncertainty regarding the optimal treatment of large nonpedunculated neoplastic lesions in the colorectum. Therefore, the comments on my article by Kanesaka et al. are highly appreciated.

Studies cited in my article [1] were certainly not randomized controlled trials [RCT], and indeed the lesions treated with endoscopic submucosal dissection (ESD) or endoscopic mucosal resection (EMR) in these studies may not be fully comparable, which I also clearly pointed out in my article. My statement pertains solely to the fact that, as of today, existing data fail to provide evidence that ESD saves more patients from surgery, and therefore the advantage of ESD over EMR in this respect needs further evaluation.

It is correct that the lesions treated with ESD tend to be larger in most series; however, this is not universally the case. For example, in the series by Terasaki et al. [2] and Kobayashi et al. [3], the mean sizes of the lesions in ESD or EMR groups were almost the same, and the mean size of lesions treated by ESD in the recent systematic review and meta-analysis [4] was only slightly but still significantly larger than the mean size of lesions resected by EMR. It is sensible to assume that larger lesions would more often end up requiring surgery; however, I know of no study to corroborate that assumption.

The need for supplementary surgery owing to the risk of lymph node metastasis in half of the patients with submucosally invasive carcinoma (SMIC) reported by Saito et al. [5] is certainly not surprising, but it might be significant; whereas most of the benign adenomas are effectively treated with EMR, ESD is primarily aimed at cure of SMIC without surgery. Several studies have shown that about half of lesions judged to be noninvasive before ESD will show unfavorable histology. In a recent top quality study [6], 52 patients were classified as SMIC. In nine of these ESD was aborted. Of the 43 patients in whom ESD was completed, 30 were considered for surgery mainly because of high risk histology. The need for surgery owing to inadequate staging after a costly and time-consuming ESD in a substantial proportion of patients with SMIC may significantly encroach on the extent of benefit supposed to be provided by ESD. Clearly, it seems that the preprocedural assessment of depth of invasion is less accurate than previously appreciated.

It is astonishing that so many years after the introduction of ESD in the colorectum, RCTs comparing EMR and ESD with respect to relevant clinical outcomes are still lacking. Systematic reviews and meta-analyses of case – control and cohort studies are the only evidence available at present. Based on these, I believe that the role of ESD in the colorectum appears not well defined, and its potential benefits still need to be properly evaluated.

• References

• 1 Rolny P. The need for surgery after endoscopic treatment of colorectal neoplasms is the most important outcome criterion. Endoscopy 2017; 49: 80-82
• 2 Terasaki M, Tanaka S, Oka S. et al. Clinical outcomes of endoscopic submucosal dissection and endoscopic mucosal resection for laterally spreading tumors larger than 20 mm. J Gastroenterol Hepatol 2012; 27: 734-740
• 3 Kobayashi N, Yoshitake N, Hirahara Y. et al. Matched case-control study comparing endoscopic submucosal dissection and endoscopic mucosal resection for colorectal tumors. J Gastroenterol Hepatol 2011; 27: 728-733
• 4 Arezzo A, Passera R, Marchese N. et al. Systemic review and meta-analysis of endoscopic submucosal dissection vs endoscopic mucosal resection for colorectal lesions. United European Gastroenterol J 2016; 4: 18-29
• 5 Saito Y, Yamada M, So E. et al. Colorectal endoscopic submucosal dissection: technical advantages compared to endoscopic mucosal resection and minimally invasive surgery. Dig Endosc 2014; 26 (Suppl. 01) 52-61
• 6 Probst A, Ebigbo A, Märkl B. Endoscopic submucosal dissection of early rectal neoplasia: experience from a European center. Endoscopy 2016;