Thyroid Cancer Screening (PDQ®)–Patient Version

Screening is looking for cancer before a person has any symptoms. This can help find cancer at an early stage. When abnormal tissue or cancer is found early, it may be easier to treat. By the time symptoms appear, cancer may have begun to spread.

Scientists are trying to better understand which people are more likely to get certain types of cancer. They also study the things we do and the things around us to see if they cause cancer. This information helps doctors recommend who should be screened for cancer, which screening tests should be used, and how often the tests should be done.

It is important to remember that your doctor does not necessarily think you have cancer if he or she suggests a screening test. Screening tests are given when you have no cancer symptoms.

If a screening test result is abnormal, you may need to have more tests done to find out if you have cancer. These are called diagnostic tests.

General Information About Thyroid Cancer

Key Points

Thyroid cancer is a disease in which malignant (cancer) cells form in the tissues of the thyroid gland.

The thyroid is a gland at the base of the throat near the trachea (windpipe). It is shaped like a butterfly, with a right lobe and a left lobe. The isthmus, a thin piece of tissue, connects the two lobes. A healthy thyroid is about the size of a walnut. It usually cannot be felt through the skin.

Anatomy of the thyroid and parathyroid glands; drawing shows the thyroid gland at the base of the throat near the trachea. An inset shows the front and back views. The front view shows that the thyroid is shaped like a butterfly, with the right lobe and left lobe connected by a thin piece of tissue called the isthmus. The back view shows the four pea-sized parathyroid glands. The larynx is also shown.

The thyroid uses iodine, a mineral found in some foods and in iodized salt, to help make several hormones. Thyroid hormones do the following:

Thyroid cancer is found more often in women.

Thyroid cancer is most often diagnosed in men and women aged 45 to 64 years. It is the most commonly diagnosed cancer in women aged 20 to 34 years. Women are about three times more likely than men to have thyroid cancer.

The number of people diagnosed with thyroid cancer in the United States had been rising for at least 40 years, but the number of deaths from thyroid cancer has stayed the same or decreased slightly. The rise in rates of thyroid cancer appears to be leveling off in recent years, and there is a decrease in the rate of thyroid tumors less than 1 centimeter in size. Most cases of thyroid cancer respond to treatment and are usually cured.

Being exposed to radiation increases the risk of thyroid cancer.

Anything that increases a person's chance of getting a disease is called a risk factor. Not every person with one or more of these risk factors will develop thyroid cancer, and it will also develop in people who don't have any known risk factors. Talk with your doctor if you think you may be at risk.

Risk factors for thyroid cancer include the following:

Thyroid Cancer Screening

Key Points

Tests are used to screen for different types of cancer when a person does not have symptoms.

Scientists study screening tests to find those with the fewest harms and most benefits. Cancer screening trials also are meant to show whether early detection (finding cancer before it causes symptoms) helps a person live longer or decreases a person's chance of dying from the disease. For some types of cancer, the chance of recovery is better if the disease is found and treated at an early stage.

There is no standard or routine screening test for thyroid cancer.

There is no standard or routine screening test used for early detection of thyroid cancer. Thyroid cancer that does not cause symptoms may be found during the following:

Screening for thyroid cancer may not help the patient live longer.

Studies have shown that screening for thyroid cancer does not decrease the chance of dying from the disease. No randomized clinical trials have been done in the United States to find out if a neck exam, ultrasound, or other screening test decreases the risk of dying from thyroid cancer. Neck exams and ultrasound are sometimes used to screen for thyroid cancer but do not decrease the risk of dying from the disease.

Screening tests for thyroid cancer are being studied in clinical trials.

Information about clinical trials supported by NCI can be found on NCI’s clinical trials search webpage. Clinical trials supported by other organizations can be found on the ClinicalTrials.gov website.

Risks of Thyroid Cancer Screening

Key Points