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About thyroid cancer

Find out about the thyroid and how common thyroid cancer is.

The thyroid gland

The thyroid is a gland that makes and releases hormones. It’s found at the base of your neck, at the front, just behind the small hollow where your collar bones meet.

The thyroid gland is in 2 halves, connected by a thinner bridge of thyroid tissue. The bridge is called the isthmus.

The 2 halves are called the lobes. Usually a cancer is found only in one lobe. But it can develop in both lobes in a type called medullary thyroid cancer.

Diagram showing the position of the thyroid gland

What it does

The thyroid gland makes the following hormones.

T3 and T4

T3 (tri iodothyronine) and T4 (thyroxine) are hormones that help control your metabolic rate, the speed of your body processes.

You might put on weight and feel very tired and lacking in energy if your thyroid gland doesn't make enough T3 and T4.

You can lose weight, despite an increased appetite, if your thyroid gland makes too much of these hormones. You might also feel anxious and find it difficult to relax.


Calcitonin works in partnership with another hormone called parathyroid hormone. Parathyroid hormone is made by parathyroid glands. These sit behind and are attached to the thyroid gland.

Calcitonin and parathyroid hormone control the amount of calcium circulating in your blood. Too much calcium can make you feel sick and drowsy. Too little can cause nerve problems, such as pins and needles, and making muscles twitch and jerk.

The parathyroid glands are left behind if you have your thyroid gland removed. But they can be affected by the operation and may take a while to get back to normal.

Your doctor will check your calcium levels regularly and might calcium supplements if you need them.

How common is it

Thyroid cancer is quite rare. Less than 1 in every 100 cancers (1%) diagnosed in the UK is a thyroid cancer. Around 3,400 people are diagnosed each year. It’s more common in women than in men.

Last reviewed: 
22 Oct 2014
  • Cancer Research UK statistics 

  • Cancer and its management (7th edition)
    J Tobias and D Hochhauser
    Blackwell, 2015

  • Cancer. Principles and practice of oncology (10th edition)
    VT De Vita, S Hellman and SA Rosenberg
    Lippincott, Williams and Wilkins, 2015, p 1175-1188

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