Neuroendocrine tumor of the midgut (MNET) has surpassed adenocarcinoma as the most common small bowel malignancy. Delayed diagnosis is common because MNET often does not lead to symptoms until the disease is either locally advanced, leading to bowel obstruction or gastrointestinal bleeding, or metastatic, resulting in carcinoid syndrome. Surgical treatment of metastatic MNET has largely been defined based on resectability of the metastatic burden. In the setting of unresectable metastatic disease, somatostatin analogues are considered the first-line approach for control of carcinoid symptoms and inhibition of tumor progression.
1 Everolimus has been shown to prolong progression-free survival for nonfunctional metastatic NET.
2 In the setting of localized liver metastases, R0 resection, debulking of more than 90% of liver disease, and/or liver-directed therapy (e.g., yttrium-90, trans-arterial chemoembolization) improve symptoms and survival.
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4 Primary tumor resection (PTR) for metastatic MNET often is considered for patients presenting with bleeding, obstruction, or ischemia. However, its role for asymptomatic patients and its impact on overall survival have been a matter of debate. Although retrospective studies have suggested a survival advantage with PTR for patients with metastatic MNET, these studies have been limited by small sample sizes, concern for selection bias toward surgical resection for patients with less advanced and less aggressive tumors, and variable inclusion of additional metastatic debulking.
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