Thyroid Cancer Screening (PDQ®)
Last modified: 2018-02-07
Last downloaded: 2018-03-20
What is screening?
Screening is looking for cancer before a person has any symptoms. This can help find cancer at an early stage. When abnormaltissue 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.
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General Information About Thyroid Cancer
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. The thyroid gland lies at the base of the throat near the trachea. It is shaped like a butterfly, with the right lobe and left lobe connected by a thin piece of tissue called the isthmus. The parathyroid glands are four pea-sized organs found in the neck near the thyroid. The thyroid and parathyroid glands make hormones.
- Control heart rate, body temperature, and how quickly food is changed into energy (metabolism).
- Control the amount of calcium in the blood.
Thyroid cancer is found more often in women.
Thyroid cancer is most often diagnosed in men and women aged 45 to 54 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 has been rising for at least 40 years, but the number of deaths from thyroid cancer has stayed the same or decreased slightly. 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 the chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn't mean that you will not get cancer. People who think they may be at risk should discuss this with their doctor.
Risk factors for thyroid cancer include the following:
- Being exposed to radiation to the head and neck as an infant or child or being exposed to radiation from an atomic bomb. The cancer may occur as soon as 5 years after exposure.
- Having a family history of thyroid disease or thyroid cancer.
- Having a history of goiter (enlarged thyroid).
- Having a geneticcondition such as multiple endocrine neoplasia type 2 syndrome (MEN2), which is caused by a change in the RET gene.
- Being female.
- Being Asian.
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Thyroid Cancer Screening
Tests are used to screen for different types of cancer.
Some screening tests are used because they have been shown to be helpful both in finding cancers early and in decreasing the chance of dying from these cancers. Other tests are used because they have been shown to find cancer in some people; however, it has not been proven in clinical trials that use of these tests will decrease the risk of dying from cancer.
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) 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.
Clinical trials that study cancer screening methods are taking place in many parts of the country. Information about ongoing clinical trials is available from the NCI website.
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:
- A routine physical exam when the doctor checks the patient's neck for lumps (nodules) or swelling in the neck, voice box, and lymph nodes, or anything else that seems unusual.
- Surgery that is done for another condition.
- An ultrasound that is done for another condition.
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.
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Risks of Thyroid Cancer Screening
Screening tests have risks.
Decisions about screening tests can be difficult. Not all screening tests are helpful and most have risks. Before having any screening test, you may want to discuss the test with your doctor. It is important to know the risks of the test and whether it has been proven to reduce the risk of dying from cancer.
The risks of thyroid cancer screening include the following:
When a screening test result leads to the diagnosis and treatment of a disease that may never have caused symptoms or become life-threatening, it is called overdiagnosis. Diagnostic tests (such as a fine-needle aspiration biopsy) and cancer treatments (such as surgery and radioactive iodinetherapy) can have serious risks, including physical and emotional problems.
Screening test results may appear to be normal even though thyroid cancer is present. A person who receives a false-negative test result (one that shows there is no cancer when there really is) may delay seeking medical care even if there are symptoms.
Screening test results may appear to be abnormal even though no cancer is present. A false-positive test result (one that shows there is cancer when there really isn't) can cause anxiety and is usually followed by more tests and procedures (such as a fine-needle aspiration biopsy), which also have risks.
Back to Top Source: The National Cancer Institute's Physician Data Query (PDQ®) Cancer Information Summaries ( http://www.cancer.gov/cancertopics/pdq)