Neuroendocrine neoplasms

Background Neuroendocrine neoplasias (NEN) are a heterogeneous group of diseases with distinct clinical presentations and prognoses. They frequently occur in the digestive tract, where they are referred to as gastroenteropancreatic (GEP) NEN. NEN account for about 1% of all malignancies and are therefore among the rare human cancers. Objective and methods Based on the literature, the current article provides an overview of the characteristics of NEN. Results Depending on their differentiation, anatomic location, size, Ki-67 proliferation index, and hormone release, GEP-NEN exhibit a wide variety of symptoms. Due to hormone excess syndromes, functionally active GEP-NEN require dedicated diagnostic strategies and treatment. Medical therapies include somatostatin analogues, targeted therapies (sunitinib, everolimus), peptide receptor radionucleotide therapy, and systemic chemotherapy. The number of phase III studies is limited, comparative trials are lacking in most cases. Therefore, a clear treatment algorithm is rarely available and treatments are applied in a sequential and individualized manner. Conclusion The therapeutic goal in differentiated neuroendocrine tumors is disease stabilization. Chemotherapy may induce partial tumor remissions in undifferentiated neuroendocrine carcinomas, but these are usually short lasting.