Thyroid Cancer Causes and Risk Factors

Page Contents

Risk factors raise your chances of getting a disease. For each person, a mix of genetic, biological and lifestyle factors play a part in thyroid cancer risk.

Take Charge of Your Health

Talk to your primary care provider if you have symptoms that you think may be ovarian cancer. UW Medicine Primary Care can help you get started. Learn about Fred Hutch's relationship with UW Medicine. 

Genetic and Biological Risk Factors for Thyroid Cancer

Biological and social risk factors include:

  • Being between 25 and 65 years old
  • Being female
  • Being Asian
  • Having a family history of thyroid cancer

Some inherited conditions are linked to an increased risk of certain types of thyroid cancer. These include, but are not limited to:

  • Multiple endocrine neoplasia type 2
  • Familial adenomatous polyposis, including Gardner syndrome
  • Cowden syndrome, also known as multiple hamartoma syndrome
  • Carney complex, a rare genetic syndrome

Lifestyle Risk Factors for Thyroid Cancer

Lifestyle risk factors for thyroid cancer include:

  • Having excess body weight
  • Iodine in the diet, either too little or too much

Previous exposure to radiation is also a risk factor. This includes exposure from certain medical treatments and tests, especially in childhood, as well as fallout from power plant accidents.

Having one or more of these risk factors does not necessarily mean you will get thyroid cancer. Many people with risk factors never develop thyroid cancer, while others with no known risk factors do.

Ways to Prevent Thyroid Cancer

The exact cause of thyroid cancer is not known. But studies show that certain factors are linked to increased risk. Some of these risk factors are things you can’t change, such as having a family history of thyroid cancer. Other factors relate to your lifestyle, so you may be able to change them. For example, having excess body weight or too much or too little iodine in the diet raises thyroid cancer risk.

Thyroid Cancer Causes and Risk Factors FAQ

Exposure to medical treatments that include radiation, especially as a child, has been linked to an increased risk of thyroid cancer.

While GLP-1 medications (semaglutides) like Ozempic include labels warning of “possible thyroid tumors, including cancer” and specifically advises those at risk for medullary thyroid carcinoma or multiple endocrine neoplastic syndrome type 2 to avoid these drugs, there have not yet been large studies on GLP-1 medications and cancer risk to come to this conclusion. “Usually many years’ follow-up of large numbers of patients are needed to see cancer effects of a carcinogen or cancer-preventing intervention like a pill,” said Fred Hutch obesity researcher Anne McTiernan, MD, PhD. Read the article on thyroid cancer risk from GLP-1 medications.

If you have any signs or symptoms that you worry might be related to thyroid cancer, talk with your primary care provider. Usually, these symptoms are caused by something else, like an infection. Whatever the cause, it’s important to find out so you can get treatment to help. If it is cancer, finding it earlier may mean it’s easier to treat.

Genetic testing may show if you have certain gene changes (mutations) that can be passed down in families and increase the risk of thyroid cancer. Tests usually involve taking a small sample of blood.

If you have a family history of thyroid cancer, ask your health care team if it’s a good idea to get tested. Your team will take into account your personal health history and your family health history before making a recommendation. If tests are recommended, you may want to speak with a genetic counselor first. They can help explain what the tests do or don’t show and what the results might mean for you.

The Clinical Genetics and Genetic Counseling Service at Fred Hutch assesses cancer risk for people who are at high risk because of their personal or family history.