Risk factors of thyroid cancer

The cause of thyroid cancer in most people are unknown, but research is going on to try to find out more.

There are a number of things that may increase your risk of developing thyroid cancer. These are called risk factors. Having a particular risk factor doesn’t mean you’ll definitely get cancer. Sometimes people without any known risk factors will develop cancer.

Benign thyroid disease

Having an overactive or underactive thyroid (hyperthyroidism and hypothyroidism) does not increase your risk of developing thyroid cancer.

However, if you have certain types of non-cancerous (benign) thyroid disease you are slightly more likely to develop thyroid cancer. These include:

  • an enlarged thyroid (goitre)
  • thyroid nodules (adenomas)
  • inflammation of the thyroid (thyroiditis).

Benign thyroid disease can run in families. You are more at risk of getting thyroid cancer if you have family members with benign thyroid disease. The risk is higher if more than one member of your family is affected.

Exposure to radiation

If you have had radiotherapy treatment to the neck area you have an increased risk of developing thyroid cancer many years later. Exposure to high levels of radiation in the environment – for example, in the areas surrounding Chernobyl in the Ukraine following the nuclear power explosion of 1986 – can also increase your risk. However, only a small number of thyroid cancers are caused by radiation exposure.

Inherited altered gene

There’s a slight increased risk of developing thyroid cancer if you have inherited an altered gene that causes a bowel condition called familial adenomatous polyposis (FAP). Family members of a person with FAP can be tested to see if they have the same altered gene.

Being female

Thyroid cancer is more common in women than men. There may be a link to female hormones.


It’s thought that people who are overweight may have a higher risk of getting thyroid cancer. A healthy diet and regular exercise may reduce the risk.