Endoscopic mucosal resection: still a reliable therapeutic option for gastrointestinal neuroendocrine tumors

Neuroendocrine tumors (NETs), as a rare and heterogeneous category of solid tumors, feature various morphologies and behaviors. In recent years, the incidence of NETs has continued to increase. Endoscopic mucosal resection (EMR) is one of the therapeutic modalities for the treatment of gastric and rectal NETs.

We evaluated patients with well-differentiated NETs of the stomach, duodenum, or rectum between 2011 and 2018. In this study, all cases with tumors confined to the mucosal or submucosal layers and smaller than 20 mm were resected using the EMR technique. We used EUS, CT scan, or MRI to exclude patients with advanced disease. All patients were actively monitored for recurrence according to the recommended protocols.

A total of 36 patients with NETs entered the study; 17 (47.2%) were female and the remaining 19 (52.8%) were male, with a total age range of 20-74 years (mean: 52.47 ± 13.47 years). Among the tumors, 31 cases (86.1%) were G1 and the remaining 5 (13.9%) were G2. Based on the pathology reports, 22 tumors (61.1%) were smaller than 1 cm, while the remaining 14 (38.9%) were between 1-2 cm. Twenty-two patients (61.1%) had a margin of specimen involved with the tumor. No recurrence was observed during the mean follow-up time of 63.5 ± 19.8 months (range: 39-103 months). All 36 cases survived during the study period.

Conventional EMR procedure provides low chance of R0 (complete resection) achievement in gastrointestinal NETs smaller than 20 mm and limited to the mucosa or sub mucosa. However, it could be an option if patients are closely followed. Postoperative marginal involvement is not a reliable predictor of disease recurrence, which may be explained by the deleterious effect of heat coagulation and cauterization applied during tumor removal.