Thyroid Cancer Treatment (PDQ®): Treatment - Patient Information [NCI] - 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 a little larger than a quarter. 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.
The thyroid uses iodine, a mineral found in some foods and in iodized salt, to help make several hormones. Thyroid hormones do the following:
- Control heart rate, body temperature, and how quickly food is changed into energy (metabolism).
- Control the amount of calcium in the blood.
There are four main types of thyroid cancer:
- Papillary thyroid cancer: The most common type of thyroid cancer.
- Follicular thyroid cancer. Hürthle cell carcinoma is a form of follicular thyroid cancer and is treated the same way.
- Medullary thyroid cancer.
- Anaplastic thyroid cancer.
See the PDQ summary on Unusual Cancers of Childhood for information about childhood thyroid cancer.
Age, gender, and exposure to radiation can affect the risk of thyroid cancer.
Anything that increases your risk 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. Talk with your doctor if you think you may be at risk. Risk factors for thyroid cancer include the following:
- Being between 25 and 65 years old.
- Being female.
- Being exposed to radiation to the head and neck as a child or being exposed to radiation from an atomic bomb. The cancer may occur as soon as 5 years after exposure.
- Having a history of goiter (enlarged thyroid).
- Having a family history of thyroid disease or thyroid cancer.
- Having certain genetic conditions such as familial medullary thyroid cancer (FMTC), multiple endocrine neoplasia type 2A syndrome, and multiple endocrine neoplasia type 2B syndrome.
- Being Asian.
Medullary thyroid cancer is sometimes caused by a change in a gene that is passed from parent to child.
The genes in cells carry hereditary information from parent to child. A certain change in a gene that is passed from parent to child (inherited) may cause medullary thyroid cancer. A test has been developed that can find the changed gene before medullary thyroid cancer appears. The patient is tested first to see if he or she has the changed gene. If the patient has it, other family members may also be tested. Family members, including young children, who have the changed gene can decrease the chance of developing medullary thyroid cancer by having a thyroidectomy (surgery to remove the thyroid).