Current treatment options for neuroendocrine tumors

Neuroendocrine tumors are heterogeneous in their clinical behavior and require therapies specially tailored according to staging and grading, origin and expression of peptide receptors. Somatostatin analogues act as antisecretory and antiproliferative agents. Chemotherapy is mandatory for poorly differentiated neuroendocrine carcinomas and is also effective in neuroendocrine tumors of the pancreas and of the bronchial system. For localized neuroendocrine tumors, surgery should be performed with curative intent and is also an option in advanced or metastasized neuroendocrine tumors with the goal to debulk tumor masses. Local ablative therapies may be applied to decrease tumor load in the liver; however, results are often of short duration. Peptide receptor radiotherapy is a new treatment method applying radionuclide-targeted somatostatin receptor agonists for internal cytotoxic radiotherapy in somatostatin receptor-expressing neuroendocrine tumors. Retrospective and prospective clinical studies indicate prolonged progression-free survival and overall survival of patients responding by stable disease or any kind of remission with this innovative treatment, which is, however, available only in a few specialized centers. Finally, small-molecule inhibitors of vascular endothelial growth factor and serine/threonine-protein kinase mTOR pathways have been shown to delay progression in patients with neuroendocrine tumors. In summary, treatment options for neuroendocrine tumors have expanded considerably in the last years leading to prolonged overall survival.