The risk factors for developing anaplastic thyroid are few and specific. The disease affects people aged 60 years and older. It affects more women than men. People who have a family history of goiters, which are swellings of the thyroid gland that are not cancerous, are also more at risk for developing thyroid cancer, as are people exposed to large doses of radiation. This might occur if someone has had radiation treatments to the head or neck or has been in close proximity to either a nuclear accident or nuclear weapons tests. Certain genetic conditions also place family members at greater risk. These conditions include medullary thyroid cancer, tumors of the endocrine glands, and certain cancers of the colon and rectum.