New and Emerging Treatment Options for Gastroenteropancreatic Neuroendocrine Tumors
Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are rare, generally indolent neoplasms that can arise throughout the gastrointestinal system. Some GEP-NETs, known as functional, secrete hormones that can lead to a complex of symptoms. Classical carcinoid syndrome is associated with flushing, diarrhea, bronchospasm, and symptoms of valvular heart disease. GEP-NETs are classified according to the primary tumor site, functionality of the disease, and histology. Treatment is guided by the resectability of the tumor, the location and extent of metastases, and the presence of clinical symptoms. Typically, first-line treatment of patients with unresectable disease includes the use of somatostatin analogs, such as octreotide LAR depot or lanreotide depot/autogel, which was recently approved by the US Food and Drug Administration for treatment of GEP-NETs. Somatostatin analogs can improve the severe diarrhea/flushing episodes that may be associated with metastatic carcinoid tumors. For patients with pancreatic NETs, additional approved treatment options include the targeted agents everolimus and sunitinib, which have demonstrated antitumor activity. Chemotherapy may also have a selective role, particularly in pancreatic NETs. Localized approaches, including cytoreductive surgery, hepatic arterial embolization, and ablative therapies, may be used for palliative treatment in patients with liver metastases.