Reply to the comments on ‘Utility of underwater endoscopic mucosal resection combined with a protruding anchor by saline injection for superficial non-ampullary duodenal tumors: a retrospective study in Japan'

We thank Yao et al.1 for their interest in our article.2 I totally agree with their opinion that this article has some limitations.1 Since superficial non-ampullary duodenal epithelial tumors are relatively rare,3,4 it was challenging to accumulate a large number of cases at a single center, resulting in a retrospective study with a limited sample size. As they kindly pointed out, we have also been considering the possibility of conducting a multicenter randomized controlled trial rather than relying solely on a single-center design. We are currently planning to move forward with a prospective multicenter randomized controlled trial.

Regarding the single case of delayed bleeding observed in our study, the patient had no relevant underlying comorbidities. We believe that bleeding may be caused by extensive mucosal resection on the anal side of the lesion due to peristaltic movement, which resulted in a large ulcer base over 40 mm in size despite conventional underwater endoscopic mucosal resection (UEMR-C).

One of the advantages of underwater endoscopic mucosal resection combined with a protruding anchor by saline injection (UEMR-A) is to form mucosal protrusion on the folds of the anal side that acts as an anchor with a favorable spring effect. This anchoring mechanism helps to avoid excessive resection, particularly on the anal side, thereby preventing an unnecessarily large ulcer base. Although we did not set inclusion criteria based on lesion size, the diameter of the respected specimen was larger in the UEMR-A group. We believe this contributes to the high rate of en bloc resection another benefit of the tip-fixation approach employed in UEMR-A.

We intend to continue accumulating further cases to reconfirm the effectiveness of this approach.