Differentiated Thyroid Cancer Incidence

There has been a dramatic increase in thyroid cancer since the early 1990's, tripling over this time period in the United States, with similar trends seen internationally. This increased incidence is almost entirely accounted for by the increased incidence of papillary thyroid cancer, with the majority of this increase due to small tumors (<1 cm). In contrast, the mortality rates associated with thyroid cancer over the same time period have remained largely stable, indicating that the increase has mainly been due to the detection of a subclinical reservoir of cancer brought about by advances in medicine. Because the incidence of large tumors has increased as well, and there has been a small uptick in deaths among people presenting with distant disease at diagnosis, it is possible there has been a simultaneous true increase in the incidence of thyroid cancer. This chapter serves to comprehensively cover the current incidence of differentiated thyroid cancer, recent incidence and mortality trends, potential contributing mechanisms for the trends observed, and the changes brought about thus far in response.