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About Thyroid Cancer

The thyroid is a butterfly-shaped gland at the base of your throat. It has two wings (lobes) on the right and the left that are connected in the middle. The thyroid gland makes, stores, and releases thyroid hormones (called T3 and T4) that affect almost every cell in your body and help regulate extremely important functions like metabolism.

Thyroid cancer is a cancerous tumour or growth in the thyroid gland. Normally, the replacement of old thyroid cells by newly produced cells is constant and regulated. In some cases, certain cells become abnormal and do not follow the regular cycle of growth. When these abnormal cells continue to grow and reproduce in an uncontrolled way, they form a tumour.

There are four main types of thyroid cancer:

  • Papillary
  • Follicular
  • Medullary
  • Anaplastic

Papillary and follicular thyroid cancers are the most common, accounting for 90% of thyroid tumours. These are often referred to as “differentiated” or “well-differentiated” thyroid cancers. The 5-year survival rate of people diagnosed with thyroid cancer is 96%, and only about 8% will have died from well-differentiated thyroid cancer-related causes 30 years after initial therapy.

Cancer of the thyroid is more common in women than in men — almost three times as many women as men get thyroid cancer. Thyroid cancer strikes people at a younger age than most other cancers — most patients are between 20 and 54 years old. The chances of recovery depend on what kind of thyroid cancer you have, where it’s located (for example, if it has spread), and your age and overall health.

The prognosis for patients with well-differentiated thyroid cancer is very good. Even after successful therapy, however, it is possible for thyroid cancer to return, sometimes decades after initial therapy. This means that it’s essential to keep going to your doctor for routine checkups — the earlier you catch a recurrence, the better the chances are for successful treatment.


There are several reasons that you or your doctor might suspect thyroid cancer. One of the most common is finding a thyroid nodule, either on your own or in a checkup. A nodule is a lump that you may feel around your thyroid. Nodules are not uncommon, and only about 5% are cancerous.

One of the most common ways to confirm thyroid cancer is with a fine needle aspiration biopsy. During this procedure, a small needle is inserted through the skin into the thyroid nodule, where it draws out a sample of the material inside the nodule. This sample is then examined under a microscope. These biopsies are quick and safe, and they don’t usually cause much discomfort.


Often, scientists cannot pinpoint the exact cause of thyroid cancer in a particular patient. Although thyroid cancer can occur in anyone, there are a few factors that have been associated with a higher risk of thyroid cancer. These include:

  • Radiation exposure to the thyroid gland, possibly from radiation therapy to the head, neck, or chest during childhood. Radiation was used far more often before 1960 to shrink enlarged tonsils or adenoids and treat skins problems like acne.
  • A family history of thyroid cancer.

Cancer management

There are many different options for managing thyroid cancer. The most common treatments include surgical removal of the cancer followed by radiation therapy (called remnant ablation) to kill both normal thyroid and thyroid cancer cells.

Surgery is the most common treatment, and may involve partial or total thyroidectomy (removal of the thyroid gland). After a total thyroidectomy, most patients undergo remnant ablation. This is an important step, since it should help clear all potentially cancerous thyroid cells that may not have been removed during surgery. In remnant ablation, patients take a drink or a capsule that contains radioactive iodine (RAI), also called radioiodine. Any remaining thyroid cells should take up the RAI, which will kill the cells. This process uses a much greater amount of radiation than a routine whole body scan, which is generally well tolerated.

After the initial treatment has been completed, patients are placed on thyroid hormone suppression therapy (THST). THST consists of taking hormones (T3 and/or T4) that essentially replace the hormones that would have been produced by the thyroid gland. This is important; in the absence of the thyroid hormones, the body tries to stimulate more thyroid activity, which increases the chances of a thyroid cancer recurrence.

During THST, the hormones take over the thyroid's role in regulating the body, meaning that patients are able to resume their lives after treatment with very few differences.


In the first few years after treatment for thyroid cancer, patients will undergo routine, frequent testing. Regular follow-ups can include:

  • Routine physical exams

  • Thyroglobulin (Tg) tests

  • Whole body scans

It is extremely important for patients to maintain a regular schedule of follow-up visits with their doctor to make sure the cancer has not returned. Even though most routine examinations don't uncover anything to be concerned about, some patients develop recurrent cancer in the thyroid area or metastatic recurrences.

Routine Testing

During follow-up tests, doctors check to see if the cancer has redeveloped. One way this is done is to check for thyroid activity in the body. The two most common follow-up tests are thyroglobulin (Tg) tests and whole body scans. Both of these can indicate the presence of thyroid activity.

A Tg test measures the amount of thyroglobulin in the blood. Patients who have had the thyroid removed (total thyroidectomy), should have little or no Tg in the blood.

A whole body scan (WBS) uses radioiodine (RAI) to check for thyroid cells. The amount of RAI used for a WBS is significantly smaller than that used for ablation, and fairly safe. About 2 days after patients have taken a drink or a capsule containing the RAI, they are scanned by a large x-ray. Any thyroid cells anywhere in the body will have taken up the RAI and will show up as spots on the x-ray film.

Both Tg testing and WBS usually require that patients have thyroid stimulating hormone (TSH) in their bloodstream to stimulate any remaining or reappearing thyroid cells. Until recently, patients had to stop taking their thyroid hormones for several weeks before after testing in order to enable the body to produce TSH. While stopping thyroid medication (becoming hypothyroid) has no noticeable effect on some people, many find the condition quite uncomfortable, and in some cases intolerable.

Fortunately, since 1998, there has been an alternative therapy that allows some patients to continue taking T3 and T4 hormones during testing and avoid the often debilitating effects of becoming hypothyroid. For more information, see the full product information.

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