Medical therapy for advanced gastro-entero-pancreatic and bronchopulmonary neuroendocrine tumors

Neuroendocrine tumors (NETs) represent a spectrum of rare neoplasms arising in different organism sites. Depending on the site of onset, they also can be distinguished using lab exams (secreting vs. nonsecreting), clinical symptoms (functioning vs. nonfunctioning), behavioral, morphological characteristics (tumor cells’ architectural growth patterns, mitotic and Ki-67 index, presence of necrosis), and grade of cellular differentiation. The aim of this review is to focus on the main signaling pathways targeted by medical treatments of advanced sporadic gastro-entero-pancreatic (GEP) and bronchopulmonary (BP) neuroendocrine neoplasms. The scientific literature regarding treatment of advanced GEP and BP-NETs has been extensively reviewed using MEDLINE and PubMed databases, selecting principal and more recent research articles, clinical trials, and updated guidelines. Somatostatin analogues represent a valid approach to control symptoms in functioning tumors and to inhibit tumor progression in certain categories on the basis of the typical somatostatin receptor expression observed in NETs. The pathogenesis of NETs has been the subject of increased interest in recent years. Many driver mutations pathway genes have been identified as important factors in the carcinogenesis process and, therefore, as potential targets for new anticancer therapies. Activating mutations have been shown in epidermal growth factor receptor, stem cell factor receptor, platelet-derived growth factor receptor, vascular endothelial growth factor, basic-fibroblastic growth factor, transforming growth factor, insulin-like growth factor-1, and their receptors. Effective M-Tor inhibition pathway modulation has led to the approval of drugs in this field such as everolimus. New drugs and several combination regimens with targeted and newer biological agents are being developed and tested in recently conducted and ongoing trials