Thyroid Cancer: Facts & Figures

Incidence in Minnesota:

Thyroid cancer has doubled in Minnesota since 1988

The incidence rate of thyroid cancer in Minnesota has doubled since 1988, following the increasing national trend. Thyroid cancer is the second most rapidly increasing cancer in Minnesota and the U.S., following melanoma of the skin. It is probable that part of the increase is due to better techniques to identify thyroid cancer, which is supported by the fact that mortality from thyroid cancer has not increased since 1988. It is the eighth most common cancer diagnosis for Minnesota females but not in the top ten for males.

From 2011 to 2013, an average of 187 new cases of thyroid cancer in males and 545 new cases in females were diagnosed in Minnesota residents each year. Each year about 25 Minnesotans die of thyroid cancer.

Thyroid cancer cases in Minnesota

Age-adjusted rate of new thyroid cancer cases.
Age-adjusted rate of new thyroid cancer cases.

The rate of thyroid cancer has increased significantly (by about 4% to 5%) in each sex since 1988 and the rate of increase became even higher in the last 10 years, with a 5.3% increase per year among females. The rate of thyroid cancer is over two- to three-times higher among females compared to males, which makes thyroid cancer one of the few cancer types where females have a greater overall risk. Most recently, the age-adjusted incidence rate of thyroid cancer was 6.7 new cases per 100,000 males and 20.3 new cases per 100,000 females.

Thyroid cancer cases in Minnesota, by age

Rate of new thyroid cancer cases, aggregated from 2004 to 2013.
Rate of new thyroid cancer cases, aggregated from 2004 to 2013.

The rate of thyroid cancer is higher overall among females compared to males. The risk of thyroid cancer increases for women through 64 years of age and then declines. Rates among males follow a more typical pattern, increasing steadily through age 80. 

What is thyroid cancer?

The thyroid gland is located at the base of the throat, below the "Adam's apple." It produces hormones that help control weight, heart rate, blood pressure and body temperature. Thyroid nodules (or bumps) are common and most, more than 90%, are not cancerous. Those that are cancerous are usually very treatable, with the exception of anaplastic thyroid cancer, a rare type making up about 1% of all thyroid cancers.

What are the risk factors for thyroid cancer?

  • Radiation: Exposure to radiation, especially as a child, is the only known risk factor. This is generally not an issue for most Minnesotans, although some may have been exposed for medical treatments or to other rare sources of radiation.
  • Sex: Thyroid cancer is one of the few cancers where females have a much higher rate than males. Since the incidence of thyroid cancer dramatically increases for young and middle-aged women, researchers suspect some hormonal/reproductive connection. 
  • A few hereditary conditions increase the risk of thyroid cancer, but these represent very few thyroid cancers.
  • Lack of iodine is a risk factor for follicular thyroid cancer, but this is not a factor in the United States since iodine is added to table salt and other foods. Other studies, however, show that too much iodine in the diet may increase the risk of papillary thyroid cancer. More studies are needed to know whether iodine is a risk factor.

How can thyroid cancer be prevented?

The cause of most thyroid cancers is unknown, so there are no proven methods to prevent most types. The only effective prevention strategy is to avoid radiation exposure (e.g., use lead shields during medical X-rays). Radiation exposure, especially in childhood, is a known risk factor for thyroid cancer. As a result, doctors no longer use radiation treatment for less serious diseases. Children, furthermore, should avoid any unnecessary x-rays. In some cases, a family history of thyroid cancer may prompt genetic testing for certain types of thyroid cancer, as some familial types can be treated early or prevented.