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Thyroid Cancer

< Head, Neck and Skin Cancer

Thyroid Cancer

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.

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

Your doctor may find a lump (nodule) in your thyroid during a routine medical exam. A thyroid nodule is an abnormal growth of thyroid cells in the thyroid. Most thyroid nodules are not cancer.

Nodules may be solid or fluid-filled. When a thyroid nodule is found, an ultrasound of the thyroid and a fine-needle aspiration biopsy are often done to check for signs of cancer. Blood tests to check thyroid hormone levels and for antithyroid antibodies in the blood may also be done to check for other types of thyroid disease. Thyroid nodules usually don't cause symptoms or need treatment. Sometimes the thyroid nodules become large enough that it is hard to swallow or breathe and more tests and treatment are needed. 

There are four main types of thyroid cancer:

  • Anaplastic thyroid cancer
  • Follicular thyroid cancer: Hürthle cell carcinoma is a form of follicular thyroid cancer and is treated the same way
  • Medullary thyroid cancer
  • Papillary thyroid cancer: The most common type of thyroid cancer


Thyroid cancer may not cause early signs or symptoms. It is sometimes found during a routine physical exam. Signs or symptoms may occur as the tumor gets bigger. Other conditions may cause the same signs or symptoms. Check with your doctor if you have any of the following:

  • A lump (nodule) in the neck
  • Hoarseness
  • Trouble breathing
  • Trouble swallowing

Risk Factors

Risk factors for thyroid cancer include the following:

  • Being Asian
  • Being between 25 and 65 years old
  • 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
  • Being female
  • Having a family history of thyroid disease or thyroid cancer
  • Having a history of goiter (enlarged thyroid)
  • Having certain genetic conditions such as familial medullary thyroid cancer (FMTC), multiple endocrine neoplasia type 2A syndrome, and multiple endocrine neoplasia type 2B syndrome

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).