Safety and efficacy of colorectal endoscopic submucosal dissection by the trainee endoscopists.

The colorectum is known to be the most difficult organ to perform endoscopic submucosal dissection (ESD), however, the training has not been sufficiently established. In our hospital, the essential condition to start colorectal ESD was to experience at least 30 gastric ESD and to have sufficient knowledge and techniques beforehand. Rectal ESD were initially performed under supervision of ESD experts. According to their technical acquisition, the ESD experts allocated lesions to the trainees from smaller lesions in the distal colon to larger lesions in the proximal colon. We retrospectively investigated the outcomes of 92 and 23 colorectal ESD performed by two trainee endoscopists (A/B) who gained experience on our training scheme. The rates of en bloc/complete resection for A and B were 92.4%/73.9% and 95.7%/65.2%, respectively. The rates of bleeding/perforation, which occurred only with A, were 1.1%/3.3%, respectively. Intraoperative perforation occurred in one case (4.3%) in the later period. In the later period, en bloc resection rate remained high in spite of the difficult lesions. Our training scheme enabled trainees to perform colorectal ESD effectively and safely from the initial period. Step-by-step accumulation of cases such as from the rectum to the colon may be desirable for the introduction of colorectal ESD.