Cancer Home > Cause of Thyroid Cancer
While a specific thyroid cancer cause is not yet known, researchers have identified certain risk factors for the disease. Some of the risk factors for thyroid cancer include such things as being exposed to high levels of radiation, eating a diet low in iodine, and being female.
No one knows the exact cause of thyroid cancer. Doctors can seldom explain why one person will get thyroid cancer and another person will not. However, it is clear that this disease is not contagious -- no one can "catch" thyroid cancer from another person. Thyroid cancer research has shown that people with certain risk factors are more likely than others to develop thyroid cancer. A risk factor is anything that increases a person's chances of developing a disease. It is important to note that risk factors do not cause thyroid cancer. However, several thyroid cancer risk factors may act together to increase a person's thyroid cancer risk.
Know the Risk Factors
Specific thyroid cancer risk factors include:
- Being exposed to high levels of radiation
- Having a family history of medullary thyroid cancer or certain other medical conditions (such as goiters)
- Being female
- Being over 40 years of age
- Being Caucasian
- Not getting enough iodine in one's diet.
Exposure to Radiation
People who are exposed to high levels of radiation are much more likely than others to develop papillary or follicular thyroid cancer.
One possible source of radiation exposure is treatment with x-rays. Between the 1920s and the 1950s, doctors used high-dose x-rays to treat children who had enlarged tonsils, acne, and other problems affecting the head and neck. Later, scientists found that some people who had received this kind of treatment developed thyroid cancer.
Routine diagnostic x-rays, such as dental x-rays or chest x-rays, use very small doses of radiation, and their benefits nearly always outweigh their risks. However, repeated exposure can be harmful, so people should talk with their dentist and doctor about the need for each x-ray and ask about the use of shields to protect other parts of their body.
Another source of radiation is radioactive fallout. This includes fallout from atomic weapons testing (such as the testing in the United States and elsewhere in the world, mainly in the 1950s and 1960s). Other sources of fallout include nuclear power plant accidents (such as the Chernobyl accident in 1986) and releases from atomic weapons production plants (such as at the Hanford facility in Washington state in the late 1940s). Such radioactive fallout contains radioactive iodine (I-131). People who were exposed to one or more sources of I-131 -- especially if they were children at the time of their exposure -- may have an increased risk for thyroid diseases.