UNDERWATER ENDOSCOPIC MUCOSAL RESECTION FOR SMALL RECTAL NEUROENDOCRINE TUMORS

Aims:

Neuroendocrine tumors arise from enterochromaffin cells. The rectum is one of the most commonly sites. Many techniques for resection of rNETs have been reported. UEMR is a technique in which the bowel lumen is filled with water and the lesion is then resected without requiring submucosal injection. Current published guidelines recommend local endoscopic resection for small rNETs with no risk factors for metastasis. However, no clear indications for type of endoscopic intervention exist. This study aimed to evaluate the efficacy and safety of UEMR in removing small rNETs.

Methods:

Retrospective study with patients who underwent UEMR in two centers between June/2015 and May/2018. UEMR was performed using a standard colonoscope. The rectal lumen was deflated and water was infused using an irrigation pump until complete filling of the lumen was achieved. All gas pockets in the operative field were evacuated. No submucosal injection was performed. Board-certified pathologists assessed histopathologic findings (histologic grade, status of resected margins, depth of invasion, lymphovascular invasions).

Results:

Over 23 months, 11 patients – 9 female (81%), mean age 55,81 years (range from 30 to 73 years) with 11 lesions (mean size 0,7 mm, range from 0,3 to 1,2 mm) underwent UEMR for small rNETs. 9 patients (81%) with G1 rNET and 2 patients with G2, all of them infiltrating the submucosa and only one restricted to mucosa. No patient had any vascular or perineural invasion. All lesions removed en bloc. 8 resections (80%) had free margins. Two patient had deep margin involvement; one of them had negative biopsies in the endoscopic surveillance. The other one lost to follow-up. No perforations or delayed bleeding occurred.

Conclusions:

In this small series, the results suggest that UEMR may be an effective and safe alternative method for small rNETs without adverse event and high en bloc and R0 resection rates.