Clinical utility of endoscopic submucosal dissection using the pocket-creation method with a HookKnife and preoperative evaluation by endoscopic ultrasonography for the treatment of rectal neuroendocrine tumors

BACKGROUND Various endoscopic methods have been developed to remove small rectal neuroendocrine tumors (NETs). This study aimed to evaluate the clinical utility of endoscopic submucosal dissection using the pocket-creation method (ESD-PCM) with a HookKnife, following preoperative evaluation by endoscopic ultrasonography (EUS), for the treatment of rectal NETs. METHODS We analyzed retrospectively consecutive patients who underwent ESD-PCM with a HookKnife for the removal of rectal NETs, with a size less than 10 mm, at Mie University Hospital between June 2015 and December 2019. All the rectal NETs were resected by ESD-PCM with a HookKnife. The R0 resection rate, procedure time, adverse event rate, diagnostic accuracy of tumor size and invasion depth evaluated by preoperative EUS, and follow-up outcome were evaluated retrospectively. RESULTS The study group comprised 12 patients with 12 resected lesions. The median tumor size of the resected specimens was 5 mm and the size and invasion depth of each tumor was approximately equal to that predicted by preoperative EUS. R0 resection was achieved in all cases, without adverse events. The median procedure time was 50.5 min, which did not differ from previous studies. No recurrence was observed during the median follow-up period of 34.4 months (range, 5.2-60.0 months). CONCLUSIONS ESD-PCM with a HookKnife provides a favorable clinical utility for removing rectal NETs, with high R0 resection rate and good follow-up outcome. In addition, EUS is useful for evaluating preoperatively the size and invasion depth of rectal NETs.