Pathogenesis of Thyroid Cancer

Thyroid cancers (TCs) include a wide spectrum of cancer types, from indolent papillary microcarcinomas, through well-differentiated TCs to aggressive and treatment-refractory poorly and undifferentiated TCs. TC, mostly papillary microcarcinoma, features one of the most rapid incidence increases compared to other malignant neoplasms. This phenomenon is mainly explained by a widespread use of diagnostic tools (neck ultrasound, fine needle aspiration biopsy). However, it is possibly also a consequence of the impact of environmental and genetic factors. This chapter summarizes the current knowledge concerning environmental and in particular molecular factors related to TC pathogenesis. The use of high throughput methods showed a wide spectrum of genetic and epigenetic alterations as well as their associations in TC. Notwithstanding our better understanding of the molecular pathology of TC, numerous questions still remain open.