Thyroid cancer is a disease in which cancer 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 patient’s 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):

• papillary
• follicular
• medullary
• 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 patient’s 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 don’t 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).

How thyroid cancer is treated

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

• Surgery
• Radiation therapy
• Hormone therapy
• Chemotherapy

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.