Efficacy and safety of modified endoscopic mucosal resection for rectal neuroendocrine tumors: a meta-analysis.

 Rectal neuroendocrine tumors are rare with good prognosis. Several endoscopic methods such as endoscopic polypectomy, endoscopic submucosal dissection (ESD), endoscopic mucosal resection (EMR), and modified endoscopic mucosal resection (m-EMR) are used in the treatment of rectal neuroendocrine tumors. Although m-EMR is derived from traditional EMR, it has not been widely used in clinical practice. In this study, we compared the efficacy and safety of EMR and m-EMR in the treatment of rectal neuroendocrine tumors by performing a meta-analysis. We searched PubMed, Web of Science, and EMBASE index up to the end of January 2017 for all published literature about EMR and m-EMR in the treatment of rectal neuroendocrine tumors. A total of 11 studies involving 811 patients were included. The pooled data suggested that there was a significantly higher rate of histologic complete resection and endoscopic complete resection among patients treated with m-EMR than those treated with EMR (histologic complete resection: OR = 0.23, 95 % CI = 0.10-0.51, p < 0.01; endoscopic complete resection: OR = 0.13, 95 % CI = 0.02-0.74, p = 0.02). The procedure time of EMR was longer than m-EMR (MD = 2.40, 95 % CI = 0.33-4.46, p = 0.02). There was a significantly higher rate of vertical margin involvement among patients treated with EMR than those treated with m-EMR; whereas, there was no significant difference of lateral margin involvement between the m-EMR and EMR groups (vertical margin involvement: OR = 5.00, 95 % CI = 2.67-9.33, p < 0.01; lateral margin involvement: OR = 1.44, 95 % CI = 0.48-4.37, p = 0.52). There was no significant difference in mean tumor size among patients treated with m-EMR versus those treated with EMR (MD = -0.30, 95 % CI = -0.75-0.14, p = 0.18); further, there was no significant difference in endoscopic mean sizes of the tumor and pathological mean sizes of the tumor between the m-EMR and EMR groups (endoscopic mean sizes of the tumor: MD = 0.20, 95 % CI = -0.44-0.84, p = 0.43; pathological mean sizes of the tumor: MD = 0.62, 95 % CI = -0.68-1.92, p = 0.05). No significant differences were detected among the treatment groups with regard to complications (bleeding: OR = 0.87, 95 % CI = 0.39-1.95, p = 0.73; complications (bleeding and perforation): OR = 0.87, 95 % CI = 0.40-1.88, p = 0.73). The efficacy of m-EMR are better than EMR among patients undergoing endoscopic treatment of rectal neuroendocrine tumors, and the safety of m-EMR is equivalent to EMR treatment.