Most people with thyroid cancer don’t have any known risk factors for it, so it is often difficult to prevent. Familial medullary thyroid carcinoma (MTC) is a genetic form of thyroid cancer that a blood test can detect. This allows doctors to prevent most cases of MTC, or to treat them early. If you have a personal or family history of goiters with thyroid nodules, you are at an increased risk of developing thyroid cancer. If you have a family history of multiple growths of the colon or rectum (familial polyposis), you are also at an increased risk. Women are approximately three times more likely than men to develop thyroid cancer. Your best chances of a cure for thyroid cancer is to start therapy when your doctor first diagnoses your cancer.
Researchers have linked thyroid cancer to radiation exposure, especially during childhood. Doctors today try to limit children's radiation exposure during medical testing and therapy. If your child needs radiation to his or her throat or upper chest area, ask what measures the doctors will take to minimize your child's future thyroid cancer risk. It is a good idea for both children and adults to avoid X-rays and other forms of radiation as much as possible. Radioactive fallout, such as from nuclear power plant accidents and atomic weapons testing, is another source of potential radiation exposure.
Too little iodine in your diet is a possible risk factor for thyroid cancer; however, some studies suggest that too much iodine may actually increase your risk for thyroid cancer. Researchers require more studies to determine the role iodine intake plays as a risk factor for thyroid cancer. In the United States, salt is voluntarily supplemented with iodine, which has reduced deficiencies. Seafood, eggs, grain products and dairy products are all good sources of iodine.