[TENpath network, an expertise pathology network dedicated to sporadic and inherited adult neuroendocrine tumors: first evaluation and first lessons].

TENpath is a network for the expert pathological diagnosis of malignant neuroendocrine tumors of the adult, both familial and sporadic, created by the French National Institute of Cancer in 2010. After 3years of activity, a first evaluation can be made. The perimeter of the network includes all neuroendocrine tumors (except small cell carcinomas of the lung), medullary carcinomas of the thyroid and extra-adrenal paragangliomas. The objectives of the network are not only the pathological review of all newly diagnosed cases of neuroendocrine tumors, but also the epidemiological surveillance, the training of pathologists, the production of recommendations and the initiation of research projects. The organisation of the network includes a database in which all referred cases are declared and a virtual expert system making it possible collegial expertises in line. Twenty-two expert centers are currently participating to TENpath. A total of 1350 cases have been referred in 2011 and 1518 in 2012. Major discrepancies amounted up to 5.9% in 2011 and to 2.9% in 2012. They mainly involved problems of differential diagnosis and wrong evaluations of the differentiation status of the tumor. The lessons to draw from the first years of TENpath are: (a) the long-standing underestimation of the actual number of patients with neuroendocrine tumors in France, (b) a better delineation, based on objective data, of the cases raising actual problems of diagnosis, (c) the existence of cases raising problems of classification even to experts and justifying a particular effort of research. These informations will be important to discuss the future evolution of TENpath.