[Thyroid cancers: from epidemiology to molecular biology]

Experts increasingly recognize the hypothesis of "over-diagnosis" as the main factor of the raising incidence of thyroid cancers (TC). The detection of multiple microtumors, mainly of a papillary type, at a sub-clinical stage, with the use of sensitive detection methods supports this hypothesis. However, the intensive management and monitoring of these cancers failed to reduce mortality. Environmental and other risk factors cannot provide a sufficient explanation, as previously thought. In this context, the use of improved tools is needed, and the most promising perspective lies in molecular biology applied to thyroid cancer for diagnosis, evaluation of prognosis and treatment. The next generation sequencing (NGS) has demonstrated its diagnostic performances in recent clinical trials. Its interest in cases with indeterminate cytology is demonstrated and should help better targeting surgical indications. Its promising prognostic and therapeutic applications must be confirmed by additional studies. The integration of NGS in current practice should have a real medical, economic and scientific impact. Indeed, the exponential increase in our knowledge of molecular mechanisms of thyroid tumorigenesis strengthens the will to "reclassify" these cancers into molecular rather than histological subtypes, in order to offer patients more specific and targeted treatment.