Treatment Outcome of Colorectal Neuroendocrine Tumor

Abstract

Background. Neuroendocrine tumors, previously known as carcinoid tumors, are the second most common malignancy in the colon and rectum. Their incidence is gradually increasing due to progressively advanced screening tools and spreading awareness of the detection of adenocarcinomas. Neuroendocrine tumors are classified according to their behavior as low (well-differentiated) and high (poorly-differentiated) grade. We analyzed the treatment outcome of colorectal neuroendocrine tumor. Methods. We retrospectively reviewed 60 patients who were diagnosed with colorectal neuroendocrine tumor between May 2005 and December 2014. The distribution of the tumor location was evaluated. For smaller tumors (＜ 2 cm), we compared the complete resection rate, complication rate, and oncologic outcome between transanal tumor resection and endoscopic submucosal dissection. For larger tumors (＞ 2 cm) or advanced disease, we analyzed the surgical morbidity, mortality, and overall survival rates as compared to nonsurgery patients. Results. Out of 60 colorectal neuroendocrine tumor patients, 10 were excluded due to incomplete information or loss of follow-up. A total of 19 patients underwent endoscopic resection and 11 underwent transanal excision of the tumor. There was no significant difference in the complete resection rate between the endoscopic and transanal groups. None of those patients had recurrent tumor during follow-up. Among 11 patients who underwent radical colectomy and lymph node dissection, 4 had distant metastasis initially and 2 (50%) died within 1 year. Of the other 7 patients without distant metastasis initially, 4 (57%) eventually had distant metastasis but only 1 (14%) died within 1 year. Of 9 patients who didnot undergo surgical treatment (all 9 had initial liver metastasis), 5 (56%) died within 1 year. There was no significant difference in overall survival between the surgery and nonsurgery groups among patients with distant metastasis. Conclusion. Small colorectal neuroendocrine tumors have a good prognosis, with no significant difference in outcome when treated by colonoscopic removal or transanal resection. For larger or high grade neuroendocrine tumors, radical surgery provided acceptable survival despite having a high risk of distant metastasis. For patients with initial stage IV disease, the 1-year survival rate was relatively low and there was no difference in outcome between the surgery and nonsurgery groups.