Thyroid cancer is a rare type of cancer that affects the thyroid gland, a small gland at the base of the neck.  The most common symptom of thyroid cancer is a painless lump or swelling that develops in your neck.

Where is the thyroid gland?

The thyroid gland sits in the front of the neck just below the voice box (larynx). It is made up of 2 main lobes (right and left) joined across the middle by a thinner strip called the isthmus. There is also a much smaller pyramidal lobe in some people. The gland is butterfly or bow tie shaped.

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What does the thyroid gland do?
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It produces thyroid hormones called thyroxine (T4) and tri-iodothyronine (T3). These hormones are very important and help control the body’s metabolism (use of energy). The thyroid gland also produces calcitonin. This helps control the amounts of calcium and phosphate salts in the body. The level of calcitonin is raised when medullary thyroid cancer is present.


How common is thyroid cancer?

Compared to breast, lung, prostate and bowel cancers thyroid cancer is much less common. In 2010, there were approximately 2654 new cases (1906 women, 748 men) diagnosed in the UK.

(Compared to breast cancer 49,961: lung cancer 42,026: bowel cancer 40,695: prostate cancer 40,975. For more information go to UK Cancer Research Stats.)

What symptoms does thyroid cancer cause?

The commonest way that thyroid cancers are found is when someone notices a lump or nodule in the neck where the thyroid gland sits. This is usually painless and many patients feel otherwise well.

It is very important to know however, that having a lump in the thyroid is quite common and most lumps are NOT thyroid cancer. In fact only about 1 person in 20 presenting with a thyroid lump will have thyroid cancer as the cause of the lump. The other lumps will be benign and hence will not contain cancer.

Other possible ways for thyroid cancer to be diagnosed include:

  • Swollen lymph glands/nodes in the neck
  • Unexpected finding when thyroid gland removed during an operation for another reason

Less common ways include:

  • Hoarse voice
  • Difficulty swallowing
  • Difficulty breathing or noisy breathing

In rare cases, the first signs may be due to the cancer having spread from the thyroid gland to other parts of the body where it produces secondary tumours (metastases). For example, the lungs or bones.

Thyroid function blood tests are usually normal in thyroid cancer and a normal test does not therefore rule out the possibility of thyroid cancer being present if there is a nodule in the thyroid.

Who is at risk?

Thyroid swellings/nodules are very common but most nodules are not cancers.

Usually it is not known why a particular person has developed thyroid cancer but there are some known risk factors. These include:

  • Previous exposure to radiation (for example children in Russia exposed to radiation from the Chernobyl accident, patients who may have had radiotherapy (x ray treatment) for a different type of cancer as a child or young adult)
  • Family history of thyroid cancer (particularly important for medullary thyroid cancer)


Category: Thyroid
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