UCSF

Key PointsThe incidence of thyroid cancer has increased over the past several decades, which, in many countries around the world, has been largely driven by new cases of papillary thyroid cancerIncreased opportunities for detection and diagnosis of small, indolent thyroid cancers seem to explain much, but not all, of the patterns in thyroid cancer incidenceResults from epidemiological studies suggest that a substantial proportion of thyroid cancer diagnoses (>40% in the USA) could be attributable to environmental factors, such as obesity and cigarette smokingClinical practice guidelines have recently changed in response to an increasing awareness of the potential for unnecessary diagnosis and treatment in a subset of patientsLarge-scale, prospective epidemiological studies and laboratory-based investigations are needed to identify modifiable risk factors for thyroid cancer and promising targets for thyroid cancer prevention