Underwater Endoscopic Mucosal Resection of a Rectal Neuroendocrine Neoplasia – a new therapeutic approach
Tiago Ribeiro1 , Francisco Mendes1 , Rui Morais1 , Guilherme Macedo1
1 – Department of Gastroenterology, Centro Hospitalar Universitário de São João, Porto, Portugal
Description
Underwater endoscopic mucosal resection (U-EMR) has recently been suggested for the treatment of rectal neuroendocrine tumors (r-NETs), as an alternative to the more invasive and less available endoscopic submucosal dissection (ESD). We present the case of a 48-year-old woman, with a significant medical history for essential hypertension and dyslipidemia, for which she was medicated with ramipril and simvastatin. The patient was referred for Gastroenterology consultation after a screening colonoscopy documented a 10 mm, regular, yellowish lesion in the middle-third of the rectum, which was suspected to represent a subepithelial lesion (Figure 1). Biopsies of the lesion revealed a well-differentiated r-NET. Endoscopic ultrasound and pelvic magnetic resonance excluded involvement of the deeper layers of the rectal wall or evidence of locoregional lymph node metastases. A 68 Ga-DOTANOC- PET/CT showed a single enhancing point at the rectum and an abdominopelvic CT scan had no evidence of distant metastasis. Multidisciplinary team consultation opted for endoscopic resection.
The patient was submitted to U-EMR (video 1-link here).
There were no procedure-related complications, and the patient was discharged from the endoscopy unit on the same day. Histopathological analysis (Figure 2) showed a r-NET with a low proliferative index (Ki-67<3%), no vascular or perineural invasion (World Health Organization Classification System NET G1 T1aR0). The patient is currently under follow up.
Figure 1.
Figure 2.
Discussion
Colorectal neuroendocrine tumors are relatively rare neoplasms, accounting for less than 2% of all colorectal cancers [1]. The rectum is the second most common location for neuroendocrine tumors (NETs) involving the gastrointestinal tract, being affected in 27% of these patients. The incidence of these lesions has risen 10-fold over the last decades, mostly due to incidental findings during colonoscopies performed for colorectal cancer screening [1]. Indeed, most patients with r-NETs are asymptomatic, have single small nodular structure within the rectal mucosa, most often with a yellowish coloration. For small lesions (<20 mm), endoscopic resection is a validated alternative for the treatment of patients with r-NETs. Nevertheless, conventional EMR techniques are associated with a suboptimal rate of R0 resections (35%), when compared to more invasive techniques such as ESD, which ensures en-bloc R0 resection in over 90% of cases [2,3]. Underwater EMR has been introduced as a less invasive alternative to ESD for the treatment of r-NETs. In this procedure, air is evacuated from the lumen and water is instilled. This generates a buoyancy effect, leading the mucosa and submucosa to float and separate from the muscularis propria. A retrospective study comparing U-EMR to ESD for the endoscopic treatment of ≤10 mm r-NETs showed similar rates of R0 resection (86% for both techniques), with shorter procedure times and a trend towards a lower rate of adverse events [4]. This evidence places U-EMR as a less invasive, safe and effective technique for the treatment of small r-NETs.
REFERENCES
1. Keating, E.; Bennett, G.; Murray, M.A.et al. Rectal neuroendocrine tumours and the role of emerging endoscopic techniques. World J Gastrointest Endosc 2023; 15: 368-375.
2. Chandan, S.; Khan, S.R.; Kumar, A.et al. Efficacy and histologic accuracy of underwater versus conventional endoscopic mucosal resection for large (>20 mm) colorectal polyps: a comparative review and meta-analysis. Gastrointest Endosc 2021; 94: 471-482.e479.
3. Chen, T.; Yao, L.Q.; Xu, M.D.et al. Efficacy and Safety of Endoscopic Submucosal Dissection for Colorectal Carcinoids. Clin Gastroenterol Hepatol 2016; 14: 575-581.
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