Clinical Outcomes of Endoscopic Mucosal Resection for Rectal Neuroendocrine Tumor

Abstract

Introduction: The incidence of rectal neuroendocrine tumors (NETs) is rapidly increasing because of the frequent use of endoscopic screening for colorectal cancers. However, the clinical outcomes of endoscopic resection for rectal NETs are still unclear. The aim of this study was to assess the histologically complete resection (H-CR) rate and recurrence after the endoscopic resection for rectal NETs. Methods: A retrospective analysis was performed in the patients who underwent endoscopic mucosal resection (EMR) of rectal NETs between January 2002 and March 2015 at Seoul National University Hospital. Primary outcomes were H-CR and recurrence rates after the endoscopic resection. H-CR was defined as free of tumor invasion in the lateral and deep margins of resected specimens. Results: Among 277 patients, 243 (88%) were treated with conventional EMR, 23 (8%) with EMR using a dual-channel endoscope, and 11 (4%) with EMR after precutting. The median tumor size was 4.96 (range, 1-22) mm in diameter and 264 (95%) of the lesions were confined to mucosa and submucosal layer. The en-bloc resection rate was 99% and all patients achieved endoscopically complete resection. The H-CR rates were 75%, 74% and 73% for conventional EMR, EMR using a dual-channel endoscope and EMR after precutting, respectively. Multivariate analysis showed that H-CR was associated with tumor size regardless of endoscopic treatment modalities (p=0.001). Of the 277 patients, 183 patients (66%) underwent at least one endoscopic follow-up. Four out of the 183 patients (2%) with endoscopic follow-up had tumor recurrence with a median of 45 months (range 2-98). There was 1 case of disease-related death occurred 167 months after the endoscopic treatment because of bone marrow failure as a result of tumor metastasis. Conclusions: Although the en-bloc resection rate was 99% in rectal NETs, H-CR rates were 72-74% for various EMR procedures. H-CR may be associated with tumor size regardless of endoscopic treatment modalities.