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Understanding thyroid cancer

 A doctor and woman look at a tablet together.

Several types of cancer may affect the thyroid gland, but most are easily detected and treated.

Cancer is not a diagnosis any of us wants to face. But, serious as it may be, when it comes to thyroid cancer there is some good news. According to the American Cancer Society (ACS), most people with thyroid cancer have an excellent prognosis. In fact, with appropriate treatment, people with early-stage disease are 90% as likely as people without the disease to live at least five years after their diagnosis.

Multiple forms

Growths, or nodules, are a common occurrence in the thyroid gland. But the majority are not cancerous, and most go unnoticed and never cause a problem.

When a thyroid tumor is cancerous, it may be one of several types.

Differentiated thyroid cancers include papillary and follicular cancers. The papillary type accounts for about 80% of all thyroid cancer, according to the ACS.

The prognosis for each of these cancers is generally very positive, especially if the cancer has not spread.

Undifferentiated (anaplastic) thyroid cancers are much less common. This type of cancer often grows and spreads quickly. It generally has a less favorable prognosis than other types of thyroid cancer.

Medullary thyroid cancer is also rare and can run in families. Medullary cancer is sometimes slow-growing but in other cases can be aggressive. Early detection and treatment improve the chance for successful treatment. If you have a family history of this type of thyroid cancer, talk to your doctor about genetic testing.

Risk factors

You are more likely to get thyroid cancer if you don't get enough iodine in your diet. However, it's rare for this to happen in the United States, as iodine is added to table salt and other foods, notes the ACS.

Radiation treatment of the head or neck during childhood—including radiation treatments for acne, for scalp fungal infections, or to shrink tonsils and adenoids—is another risk factor for the disease.

Some people inherit a genetic predisposition for thyroid cancer. And certain inherited medical conditions, such as Gardner syndrome and familial adenomatous polyposis, also increase the risk.

Thyroid cancer is also almost three times more common in women than in men.


Several treatments for thyroid cancer are available. A combination of treatments may be needed:

  • Surgery to remove all or part of the thyroid gland and, sometimes, nearby lymph nodes is the most common treatment.
  • Radioactive iodine treatment delivers a direct dose of radiation to the cancerous cells.
  • External radiation therapy, chemotherapy and targeted drug therapy may also be used.

People who have had their thyroid totally removed will also need to take thyroid hormone therapy. This replaces the thyroid hormone that the gland is no longer able to produce. Those who've had partial removal of the gland may also need this therapy.

Follow-up is essential

Long-term follow-up is crucial after treatment for thyroid cancer. The disease may recur years or even decades later.

Your doctor may recommend a variety of tests depending on the type of thyroid cancer you had. These may include periodic chest x-rays, blood tests, thyroid ultrasounds and radioactive iodine scans. Talk to your doctor about follow-up testing and the best schedule for you.

Reviewed 12/16/2021

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