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Thyroid cancer

Published by Bupa's health information team, February 2008.

This factsheet is for people who have thyroid cancer, or who would like information about it.

A thyroid tumour is a lump created by an abnormal and uncontrolled growth of cells. It can either be malignant (cancerous) or benign.

• Animation - How cancer develops
• About thyroid cancer
• Types of thyroid cancer
• Symptoms
• Causes
• Diagnosis
• Treatment
• Living with thyroid cancer
• Questions and answers
• Related topics
• Further information
• Sources

How cancer develops

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About thyroid cancer

The thyroid

Thyroid cancer is rare but can occur at any age. It's most common in women aged 30 to 55 and over 70. In men, increasing age increases risk. It's very rare in children.

Around 1,550 people in the UK are diagnosed with thyroid cancer each year. In the UK, thyroid cancer is three times more likely in women than men.

The thyroid gland is an endocrine gland. This means that it secretes hormones into your bloodstream. Hormones are chemicals produced by the body to help regulate how cells and organs work. They are sometimes referred to as chemical messengers.

The thyroid gland is in your neck in front of the windpipe. It's about two to four centimetres long.

The position of the thyroid gland and surrounding structures

What is thyroid cancer?

Cancerous tumours can grow through your thyroid gland and spread to other parts of your body (through the bloodstream or the lymph system) where they may grow and form secondary tumours. This spread of cancer is called metastasis.

Benign tumours don't spread to other areas of the body.

Types of thyroid cancer

There are several different types of thyroid cancer.

• Papillary thyroid cancer is slow growing and sometimes spreads to the lymph nodes of the neck. Six out of every 10 thyroid cancers are papillary. Younger women are most commonly affected.
• Follicular thyroid cancer often spreads to other parts of the body such as the lung or bones. This is common and affects about three in 20 people with thyroid cancer. Younger and middle aged people are most often affected.

The papillary and follicular types are sometimes grouped together and are called differentiated thyroid cancer.

• Medullary thyroid cancer can spread to other parts of body, such as the lungs and bones. This is rare and affects about one in 20 people with thyroid cancer. Of this number, a quarter of people with medullary thyroid cancer inherit a faulty gene from a family member that causes this type of cancer.
• Anaplastic thyroid cancer grows quickly and is more difficult to treat. About three in 20 people with thyroid cancer have this type. It's more common in older women.
• Lymphoma is a cancer of the lymphatic system and can affect the lymph tissue of the thyroid gland. This usually affects people over 65 and is rare.

Symptoms

If you have thyroid cancer, you may have some of the following symptoms:

• swelling in the neck
• discomfort in the neck
• difficulty swallowing
• breathing problems
• a hoarse voice

Sometimes there are additional symptoms for medullary thyroid cancer. These can include diarrhoea and redness of the face.

Although not necessarily a result of thyroid cancer, if you have any of these symptoms you should visit your GP.

Causes

The causes of thyroid cancer aren't fully understood at present. There are, however, certain factors that make thyroid cancer more likely and these are listed below.

• People with a history of benign (non-cancerous) thyroid disease, such as an enlarged thyroid or inflammation of the thyroid, have an increased risk of thyroid cancer.
• Radiation exposure in the environment or from radiotherapy, particularly in childhood, can increase the risk of thyroid cancer.
• People who don't get enough iodine in their diet are more likely to get thyroid cancer. An unhealthy diet may also contribute. Eating less fatty foods like cheese and more vegetables which contain antioxidants (such as vitamin C and E) may help reduce your risk.
• Medullary thyroid cancer can be passed through families by certain faulty genes. It may be possible for the thyroid gland to be removed if you test positive for an abnormal cancer-causing gene before you have any symptoms of cancer. An inherited bowel condition called familial adenomatous polyposis (FAP) can also increase the risk of thyroid cancer.
• Pregnant women who have had a baby in the past two years have a slightly higher risk of papillary thyroid cancer. This is due to the increased production of thyroid stimulating hormones in the thyroid gland during pregnancy. This risk increases if you have had two or more children in five years.
• If you are taking, or have taken, the contraceptive pill and are going through the menopause or you have had a hysterectomy (removal of the womb), you may also have a slightly increased risk of thyroid cancer.

Diagnosis

Your doctor will ask you about your symptoms and will examine you. Your GP may arrange blood tests and refer you to a doctor who specialises in thyroid cancer, such as an ear, nose and throat specialist, for further tests including the following.

• A blood sample may be taken to check, for example, the thyroid hormone levels in your blood.
• An ultrasound scan of your neck uses high frequency sound waves to produce an image of the thyroid to look for signs suggesting cancer or a non-cancerous cause for the lump.
• A CT (computerised tomography) scan uses X-rays to make a three-dimensional picture of the body. This can help your doctor see how far the cancer has spread (if at all). For more information, please see Related topics.
• A thyroid radioisotope scan involves an injection into a vein in your arm of a slightly radioactive substance. This won't cause you any harm. This substance shows areas of cancer when your neck is viewed under a scan. Normal cells take up the substance; cancer cells don't.
• A biopsy is a small sample of tissue. Your doctor may use an ultrasound scan to guide a needle to the thyroid gland to take a biopsy. Alternatively, a small operation may be performed under general or local anaesthetic, where a small cut is made in your neck and a biopsy is taken from the thyroid gland. This will be sent to a laboratory for testing.

The results of the tests will determine your course of treatment.

Treatment

The treatment for thyroid cancer depends on the type, size and stage of thyroid cancer you may have.

Surgery

This may involve the removal of part, or more usually, all of the thyroid gland. Lymph glands near the thyroid gland may also be removed. The type of surgery will depend on how far the cancer has spread. See Related topics for more information.

Internal radiotherapy

This may be used if the cancer has already spread to other parts of your body or to increase the chance of cure after removal of the thyroid gland. Radioactive iodine is taken as a drink, tablet or is injected into the body. Unlike normal cells, thyroid cancer cells take in radioactive iodine and this kills them. The treatment is given in hospital as you remain slightly radioactive for a few days.

External radiotherapy

This may be the first course of treatment for medullary or anaplastic thyroid cancer, or used along with radioiodine in other types of thyroid cancer. Beams of radiotherapy are directed at the neck. A course of treatment will be required.

Chemotherapy medicines

Medicines to attack cancer cells are given for certain types of cancer. These are rarely used in thyroid cancer but may be used if the cancer has spread or comes back after other treatment.

Living with thyroid cancer

You will need to take hormone replacement medicines for life after most thyroid cancer treatment. This is to replace those that would have naturally been in the body if the thyroid gland was functioning normally. After treatment for the cancer, you may have regular check ups with your doctor to detect any evidence of the cancer returning.

Related topics

• Chemotherapy
• CT scan
• Radiotherapy
• Thyroidectomy

Further information

• Cancerbackup
  0808 800 1234
  www.cancerbackup.org.uk

Sources

• Cassidy J, Bissett D and Spence RAJ, Oxford Handbook of Oncology: Oxford University Press 2002:376-378
• Guidelines for the management of thyroid cancer in adults. British Thyroid Association and the Royal College of Physicians. March 2002. www.british-thyroid-association.org
• Improving outcomes in head and neck cancer. National Institute of Health and Clinical Excellence (NICE). http://guidance.nice.org.uk, accessed 19 July 2007
• Souhami R, Tobias J. Cancer and its management. 5th ed. Oxford, 2005:350-359
• Thyroid cancer. Cancerbackup. www.cancerbackup.org.uk, accessed 18 July 2007
• Thyroid cancer. Cancer Research UK. www.cancerhelp.org.uk, accessed 19 July 2007
• UK thyroid cancer statistics. Cancer Research UK. http://info.cancerresearchuk.org, accessed 18 July 2007

This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.

Publication date: February 2008