About thyroid cancer

What is the thyroid?

Your thyroid is a gland at the base of your neck, just below your Adam´s apple. It sits on top of your windpipe and below your voicebox (larynx). It is shaped like a butterfly because the gland is in two halves. They are connected by a narrow bridge of thyroid tissue called the isthmus. The two halves are called the lobes of the thyroid.

Your thyroid makes hormones that keep your heart rate, blood pressure, body temperature and weight at the right levels.

Your thyroid needs a regular supply of iodine to make these hormones. Iodine is mainly found in fish, seafood and dairy products.

What is thyroid cancer?

Thyroid cancer happens when cells in your thyroid change and start to grow in an abnormal way. A group of these cancer cells can form a tumour. A malignant tumour is also known as cancer. If a malignant tumour is not treated, it will affect how your thyroid works. There are five main types of thyroid cancer:

  • Papillary thyroid cancer is a very slow growing cancer. About 4 out of 5 thyroid cancers are papillary so it is the most common type. It has a high cure rate.
  • Follicular thyroid cancer is less common and usually found in older people.
  • Medullary thyroid cancer is a rare type of thyroid cancer that can run in families. If you have this type of cancer, your family members should be checked regularly.
  • Anaplastic thyroid cancer is also a rare cancer. Most people who get this cancer are older. It grows quickly and can be difficult to treat.
  • Hurthle cell cancer is a rare type of thyroid cancer. About 4 out of every 100 cases are this type. They are sometimes present in people with benign thyroid disease.

How common is thyroid cancer?

Thyroid cancer is a rare cancer that affects people who are middle aged or older. It is more common in women than men. Thyroid cancer seems to be getting more common in recent years. Doctors believe this is because new technology lets them find small thyroid cancers that were harder to find before.
In 2017 it was estimated that 276 people in Ireland are diagnosed with thyroid cancer each year. It is more common in women than men.

For more information please read our information booklet on Understanding Cancer of the Thyroid (pdf, 2.5MB)