Underwater endoscopic mucosal resection: a new endoscopic method for resection of rectal neuroendocrine tumor grade 1 (carcinoid) ≤ 10 mm in diameter

Abstract

Background and study aims Rectal neuroendocrine tumors grade 1 (NET G1; carcinoid) ≤ 10 mm in diameter often extend into the submucosa, making their complete histological resection difficult using endoscopic techniques. Endoscopic submucosal resection with a ligation device (ESMR-L) and endoscopic submucosal dissection (ESD) are commonly used to overcome these difficulties. We also previously reported that underwater endoscopic mucosal resection (UEMR) could facilitate resection of rectal NET G1. This study aimed to evaluate the safety and efficacy of UEMR for removing rectal NET G1 ≤ 10 mm in diameter. 6 consecutive patients with rectal NET G1 ≤ 10 mm in diameter underwent UEMR at our hospital. The rate of en bloc resection was 100 %, and the rate of R0 resection was 83 %. The median procedure time was 8 min (range 5 – 12 min). No perforations or delayed bleeding occurred in this study. In conclusion, UEMR allows the safe and reliable resection of rectal NET G1 ≤ 10 mm in diameter with comparable results to ESMR-L or ESD, including high en bloc and R0 resection rates with no increase in significant adverse events. A multicenter trial is required to confirm the validity of the present results.

Management of Gastrointestinal Neuroendocrine Tumors

“…The 6-month follow-up colonoscopy in non-R0 resection patients showed no residual tumor. 109 Transanal endoscopic microsurgery (TEM) may also be considered for <20-mm lesions superficial to the muscularis propria. In this procedure, a full-thickness resection can be performed transanally and the defect closed by a continuous running suture.…”

Comparison of underwater and conventional endoscopic mucosal resection for removing sessile colorectal polyps: a propensity-score matched cohort study

“…In contrast to standard EMR, UEMR does not require a submucosal injection because the buoyancy effect on the adenoma-bearing mucosa raises it from the deeper muscularis propria. During the past 6 years, about 30 studies on UEMR were published, and they indicated the usefulness of UEMR for large sessile colon polyps, 11 polyps in difficult locations, 12 13 14 duodenal non-ampullary adenomas, 15 neuroendocrine tumors, 16 17 and recurrent colorectal polyps 18 . However, only three reports compared clinically relevant outcomes of colorectal UEMR and standard EMR.…”

Anchoring the snare tip is a feasible endoscopic mucosal resection method for small rectal neuroendocrine tumors

“…Recently, other techniques for endoscopic resection of rectal NET were introduced. Underwater EMR (UEMR) is a novel modified EMR method that can promote the lifting and floating away of a submucosal tumor from muscularis propria by buoyancy 25 . In a retrospective study analyzing small rectal NETs (≤ 10 mm), UEMR achieved 86.1% of histologic complete resection rate comparable to ESD.…”