Medicinal therapy of metastasized neuroendocrine tumors of the gastroenteropancreatic system

Neuroendocrine neoplasms of the gastroenteropancreatic system are classified according to the WHO classification system 2010 into neuroendocrine tumors (NET) and neuroendocrine carcinomas (NEC). The proliferation index Ki-67 and the grading of NETs is essential for the prognosis and therapy plan. Also NET tumor biology and therapeutic options may differ depending on the primary NET tumor location. Palliative therapy of inoperable NETs involves local ablative methods in cases of primary liver metastasis, peptide receptor radionuclide therapy (PRRT) in NETs expressing somatostatin receptors and different options for medicinal therapy. This manuscript reviews the current role of biotherapy with somatostatin analogues and interferon-alpha for symptom and tumor control. In addition conventional chemotherapy regimens and novel molecular targeted therapeutic options, such as sunitinib or everolimus in NET of the pancreas are reviewed. Possible therapeutic algorithms are discussed.