SEOM clinical guidelines for the diagnosis and treatment of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) 2014

GEP-NENs are a challenging family of tumors of growing incidence and varied clinical management and behavior. Diagnostic techniques have substantially improved over the past decades and significant advances have been achieved in the understanding of the molecular pathways governing tumor initiation and progression. This has already translated into relevant advances in the clinic. This guideline aims to provide practical recommendations for the diagnosis and treatment of GEP-NENs. Diagnostic workup, histological and staging classifications, and the different available therapeutic approaches, including surgery, liver-directed ablative therapies, peptide receptor radionuclide therapy, and systemic hormonal, cytotoxic or targeted therapy, are briefly discussed in this manuscript. Clinical presentation (performance status, comorbidities, tumor-derived symptoms and hormone syndrome in functioning tumors), histological features [tumor differentiation, proliferation rate (Ki-67), and expression of somatostatin receptors], disease localization and extent, and resectability of primary and metastatic disease, are all key issues that shall be taken into consideration to appropriately tailor therapeutic strategies and surveillance of these patients.