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Thyroid Cancer

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What is thyroid cancer?

Thyroid cancer is a disease in which cancer (malignant) cells are found in the tissues of the thyroid gland. The thyroid gland is at the base of the throat. It has two lobes, one on the right side and one on the left. The thyroid gland makes important hormones that help the body function normally.

Certain factors may increase the risk of developing thyroid cancer.

  • Thyroid cancer occurs more often in people between the ages of 25 and 65 years.

  • People who have been exposed to radiation or received radiation treatments to the head and neck during infancy or childhood have a greater chance of developing thyroid cancer. The cancer may occur as early as 5 years after exposure or may occur 20 or more years later.

  • People who have had goiter (enlarged thyroid) or a family history of thyroid disease have an increased risk of developing thyroid cancer.

  • Thyroid cancer is more common in women than in men.

  • Asian people have an increased risk of developing thyroid cancer.

A doctor should be seen if there is a lump or swelling in the front of the neck or in other parts of the neck.

If there are symptoms, a doctor will feel the patientís thyroid and check for lumps in the neck. The doctor may order blood tests and special scans to see whether a lump in the thyroid is making too many hormones. The doctor may want to take a small amount of tissue from the thyroid. This is called a biopsy. To do this, a small needle is inserted into the thyroid at the base of the throat and some tissue is drawn out. The tissue is then looked at under a microscope to see whether it contains cancer.

There are four main types of thyroid cancer (based on how the cancer cells look under a microscope):

  1. papillary
  2. follicular
  3. medullary
  4. anaplastic

Some types of thyroid cancer grow faster than others. The chance of recovery (prognosis) depends on the type of thyroid cancer, whether it is in the thyroid only or has spread to other parts of the body (stage), and the patientís age and overall health. The prognosis is better for patients younger than 40 years who have cancer that has not spread beyond the thyroid.

The genes in our cells carry the hereditary information from our parents. An abnormal gene has been found in patients with some forms of thyroid cancer. If medullary thyroid cancer is found, the patient may have been born with a certain abnormal gene which may have led to the cancer. Family members may have also inherited this abnormal gene. Tests have been developed to determine who has the genetic defect long before any cancer appears. It is important that the patient and his or her family members (children, grandchildren, parents, brothers, sisters, nieces and nephews) see a doctor about tests that will show if the abnormal gene is present. These tests are confidential and can help the doctor help patients. Family members, including young children, who donít have cancer, but do have this abnormal gene, may reduce the chance of developing medullary thyroid cancer by having surgery to safely remove the thyroid gland (thyroidectomy).

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Stage Explanation

Stages of thyroid cancer

Once thyroid cancer is found (diagnosed), more tests will be done to find out if cancer cells have spread to other parts of the body. This is called staging. A doctor needs to know the stage of the disease to plan treatment.

Papillary and follicular thyroid cancer

The following stages are used for papillary and follicular thyroid cancer:

Stage I

  • In patients younger than 45 years, cancer may have spread within the neck or upper chest and/or to nearby lymph nodes but not to other parts of the body.
  • In patients aged 45 years and older, the tumor is 2 centimeters (about ĺ inch) or smaller and in the thyroid only.

Stage II

  • In patients younger than 45 years, the cancer has spread to distant parts of the body, such as the lung or bone, and may have spread to nearby lymph nodes.
  • In patients aged 45 years and older, the tumor is larger than 2 centimeters but not larger than 4 centimeters (between ĺ and 1Ĺ inches) in the thyroid only.

Stage III

The cancer is found in patients aged 45 years or older. The tumor either:

  • is larger than 4 centimeters; or
  • may be any size and has spread just outside the thyroid and/or to lymph nodes in the neck.

Stage IVA

The cancer is found in patients aged 45 years or older. The tumor may be any size and has spread within the neck and/or to lymph nodes in the neck or upper chest.

Stage IVB

The cancer is found in patients aged 45 years or older. The tumor may be any size and has spread to neck tissues near the backbone or around blood vessels in the neck or upper chest. Cancer may have spread to lymph nodes.

Stage IVC

The cancer has spread to other parts of the body, such as the lung or bone, and may have spread to nearby lymph nodes.

Medullary thyroid cancer

The following stages are used for medullary thyroid cancer:

Stage 0

No tumor is found in the thyroid but the cancer is detected by screening tests. Stage 0 is also called carcinoma in situ.

Stage I

The tumor is 2 centimeters or smaller and in the thyroid only.

Stage II

The tumor is larger than 2 centimeters but not larger than 4 centimeters and is in the thyroid only.

Stage III

The tumor either:

  • is larger than 4 centimeters; or
  • may be any size and has spread just outside the thyroid and/or to lymph nodes in the neck.

Stage IVA

The tumor may be any size and has spread within the neck and/or to lymph nodes in the neck or upper chest.

Stage IVB

The tumor may be any size and has spread to neck tissues near the backbone or around blood vessels in the neck or upper chest. Cancer may have spread to lymph nodes.

Stage IVC

Cancer has spread to other parts of the body, such as the lung or bone, and may have spread to nearby lymph nodes.

Anaplastic thyroid cancer

Anaplastic thyroid cancer is considered to be stage IV thyroid cancer. It grows quickly and has usually spread within the neck when it is found. Anaplastic thyroid cancer develops most often in older people.

Recurrent thyroid cancer

Recurrent disease means that the cancer has come back (recurred) after it has been treated. It may come back in the thyroid or in other parts of the body.

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Treatment Option Overview

How thyroid cancer is treated

There are treatments for all patients with thyroid cancer. Four types of treatment are used:

  • Surgery (taking out the cancer).

  • Radiation therapy (using high-dose x-rays or other high-energy rays to kill cancer cells).

  • Hormone therapy (using hormones to stop cancer cells from growing) .

  • Chemotherapy (using drugs to kill cancer cells).

Surgery is the most common treatment of thyroid cancer. A doctor may remove the cancer using one of the following operations:

  • Lobectomy removes only the side of the thyroid where the cancer is found. Lymph nodes in the area may be taken out (biopsied) to see if they contain cancer.

  • Near-total thyroidectomy removes all of the thyroid except for a small part.

  • Total thyroidectomy removes the entire thyroid.

  • Lymph node dissection removes lymph nodes in the neck that contain cancer.

Radiation therapy uses high-energy x-rays to kill cancer cells and shrink tumors. Radiation for thyroid cancer may come from a machine outside the body (external radiation therapy) or from drinking a liquid that contains radioactive iodine. Because the thyroid takes up iodine, the radioactive iodine collects in any thyroid tissue remaining in the body and kills the cancer cells.

Hormone therapy uses hormones to stop cancer cells from growing. In treating thyroid cancer, hormones can be used to stop the body from making other hormones that might make cancer cells grow. Hormones are usually given as pills.

Chemotherapy uses drugs to kill cancer cells. Chemotherapy may be taken by pill, or it may be put into the body by a needle in the vein or muscle. Chemotherapy is called a systemic treatment because the drug enters the bloodstream, travels through the body, and can kill cancer cells outside the thyroid.

Treatment by stage

Treatment of thyroid cancer depends on the type and stage of the disease, and the patientís age and overall health.

Standard treatment may be considered because of its effectiveness in patients in past studies, or participation in a clinical trial may be considered. Not all patients are cured with standard therapy and some standard treatments may have more side effects than are desired. For these reasons, clinical trials are designed to find better ways to treat cancer patients and are based on the most up-to-date information.

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Stage I and II Papillary and Follicular Thyroid Cancer

Treatment may be one of the following:

  1. Surgery to remove the thyroid (total thyroidectomy). This may be followed by hormone therapy and radioactive iodine.
  2. Surgery to remove one lobe of the thyroid (lobectomy), followed by hormone therapy. Radioactive iodine also may be given following surgery.

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Stage III Papillary and Follicular Thyroid Cancer

Treatment may be one of the following:

  1. Surgery to remove the entire thyroid (total thyroidectomy) and lymph nodes where cancer has spread.
  2. Total thyroidectomy followed by radiation therapy with radioactive iodine or external-beam radiation therapy.

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Stage IV Papillary and Follicular Thyroid Cancer

Treatment may be one of the following:

  1. Radioactive iodine.
  2. External-beam radiation therapy.
  3. Surgery to remove the cancer from places where it has spread.
  4. Hormone therapy.
  5. A clinical trial of new treatments, including chemotherapy.

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Medullary Thyroid Cancer

Treatment may be one of the following:

  1. Total thyroidectomy for tumors in the thyroid only. Lymph nodes in the neck may also be removed.
  2. Radiation therapy for tumors that come back in the thyroid as palliative treatment to relieve symptoms and improve the patient's quality of life.
  3. Chemotherapy for cancer that has spread to other parts of the body, as palliative treatment to relieve symptoms and improve the patient's quality of life.

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Recurrent Thyroid Cancer

The choice of treatment depends on the type of thyroid cancer the patient has, the kind of treatment the patient had before, and where the cancer comes back. Treatment may be one of the following:

  1. Surgery with or without radioactive iodine. A second surgery may be done to remove tumor that remains.
  2. Radioactive iodine.
  3. External-beam radiation therapy or radiation therapy given during surgery to relieve symptoms caused by the cancer.
  4. Chemotherapy.
  5. Clinical trials of new treatments.

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Thyroid Cancer