Classification of Gastroenteropancreatic Neuroendocrine Tumors

Classification of Gastroenteropancreatic Neuroendocrine Tumors Neuroendocrine tumors (NET) can arise in almost all organs. They share several biological features; however, they also differ depending on tumor localization, histopathology, functional activity, and hereditary background. A uniform nomenclature regarding classification, grading, and staging of these rare tumors is therefore mandatory to allow comparison of different international studies and the development of standardized therapy guidelines. The application of the World Health Organization (WHO) classification and the tumor, node, metastasis (TNM) staging is therefore recommended for all NET. The current existence of 2 competing TNM classifications (European Neuroendocrine Tumor Society (ENETS) and American Joint Committee on Cancer/International Union against Cancer (AJCC/UICC)) is unfortunate and requires special attention of pathologists and clinicians in the definite classification and prognostic prediction of a NET.