Factors that may increase the risk of thyroid cancer include:
• Female sex: Thyroid cancer is more common in women than in men.
• Exposure to high levels of radiation: Examples of exposure to high levels of radiation include radiation treatments for head and neck cancer, and fallout from sources such as nuclear power plant accidents and nuclear weapons testing.
• Certain inherited genetic syndromes: The genetic syndromes that increase the risk of thyroid cancer are familial medullary thyroid cancer and multiple endocrine neoplasia.