The risk of developing thyroid cancer in women is fairly constant between the age of 30 and 55, after which the risk falls. But for men, the risk of developing thyroid cancer goes up with age until 75 years. South Asian women are at a higher risk of developing thyroid cancer.
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.
The thyroid gland is an endocrine gland. It produces hormones that travel around your body in your bloodstream. Hormones are chemicals produced by the body to help control how your cells and organs work. They are sometimes called chemical messengers.
The main hormones produced in your thyroid gland are thyroxine (T4) and triiodothyronine (T3). They influence the speed at which your body processes and uses energy. This is sometimes called your metabolic rate. Hyperthyroidism (overactive thyroid) and hypothyroidism (underactive thyroid) are common problems associated with the levels of T3 and T4. Another hormone, called calcitonin is produced in your thyroid gland. Calcitonin works with parathyroid hormone, which is made by the parathyroid glands. Together they help to control the amount of calcium in your body, which is important for healthy bones and nerves.
The thyroid gland is in your neck in front of your windpipe. It's quite small and flat and often difficult to see or feel.
Cancerous tumours can grow through your thyroid gland and sometimes spread to other parts of your body (through your bloodstream or the lymph system) where they may grow and form secondary tumours. This spread of cancer is called metastasis.
Benign tumours aren't cancerous and don't spread to other areas of the body.
There are four main types of thyroid cancer. These are listed below. The papillary and follicular types are sometimes grouped together and are called differentiated thyroid cancer.
- Papillary thyroid cancer is the most common type of thyroid cancer. It's usually slow growing and is most common in women and in younger people.
- Follicular thyroid cancer is less common than papillary thyroid cancer and usually affects slightly older people. It can spread to other parts of the body such as the lung or bones.
- Anaplastic thyroid cancer is also rare. It tends to grow more quickly than other types of thyroid cancer and can be more difficult to treat. About three in 20 people with thyroid cancer have this type. It's more common in older people and women.
- Medullary thyroid cancer is rare and affects about one in 20 people with thyroid cancer. For around one in every four people with medullary thyroid cancer it's a hereditary condition, which means it's passed down through family generations. It can spread to other parts of body, such as the lungs and bones.
It's also possible to get another type of cancer, called lymphoma in your thyroid gland, although this is rare.
Lumps in the thyroid gland are quite common. For example, nine out of 10 women over the age of 70 will have a thyroid lump. If you have thyroid cancer, you may have some of the following symptoms:
- a painless lump in your neck, which gradually gets bigger
- difficulty swallowing
- breathing problems
- a hoarse voice
Medullary thyroid cancer can cause other symptoms including diarrhoea and redness of the face.
These symptoms can be caused by problems other than thyroid cancer. If you have any of these symptoms, visit your GP for advice.
The causes of thyroid cancer aren't fully understood at present. There are, however, certain factors that make developing thyroid cancer more likely. The following factors may increase your risk of the disease.
- History of non-cancerous (benign) thyroid disease, such as an enlarged thyroid or inflammation of the thyroid.
- Radiotherapy to the neck area, particularly if this was done at a young age.
- Not enough iodine in the diet.
- An inherited bowel condition called familial adenomatous polyposis (FAP).
- Family history of medullary thyroid cancer.
Your GP will ask you about your symptoms and will examine you. He or she may also ask you about your medical history and arrange initial blood tests. If your GP thinks you may have a thyroid tumour then you will be referred to a doctor who specialises in thyroid cancer for further tests. The main tests may include the following.
- A blood sample to check, for example, the thyroid hormone levels in your blood.
- An ultrasound scan of your neck which uses sound waves to produce an image of the thyroid.
- A biopsy of a lump in your thyroid. A biopsy is a small sample of tissue. Your doctor may use an ultrasound scan to guide a needle to the thyroid lump to take a biopsy. Alternatively, a small operation may be performed under general or local anaesthesia, 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 to find out if the cells are benign (not cancerous) or cancerous.
The results of your tests will decide the treatment you need. If you have cancer, you may need to have other tests to assess if the cancer has spread. The process of finding out the stage of a cancer is called staging.
The treatment for thyroid cancer depends on the type, size and stage of thyroid cancer you have.
An operation to remove all or part of the thyroid gland is the most common treatment for thyroid cancer. This is called a thyroidectomy. Lymph glands near your thyroid gland may also be removed. The type of surgery you have will depend on how far the cancer has spread.
Radioactive iodine treatment
Most people will need to have radioactive iodine treatment after surgery. This is to make sure that all the cancer cells are destroyed. Radioactive iodine is swallowed as a drink or tablet or it can be injected into your body. The thyroid cancer cells take in the radioactive iodine and this kills them, without affecting other cells in your body.
This treatment is given in hospital and you may need to stay there for a few days in a single room. This is because you will remain slightly radioactive for a few days after the treatment and should limit the time you spend with other people.
Radiotherapy is a treatment to destroy cancer cells with radiation. A beam of radiation is targeted on the cancerous cells, and shrinks the tumour. It may be the first course of treatment for anaplastic thyroid cancer, or may be used along with radioiodine in other types of thyroid cancer. Radiotherapy can also be used to treat a tumour, or part of a tumour that can't be removed with surgery. Radiotherapy is given as a course of treatment over a number of weeks.
Chemotherapy uses medicines to destroy cancer cells. It's not often used to treat thyroid cancer but may be used if the cancer has spread or comes back after other treatment.
After your treatment
If you have had surgery to remove your thyroid gland, or if you have had some of the other treatments for thyroid cancer, you will need to take hormone replacement medicines for life. This is to replace the hormones that would have naturally been in your body if your thyroid gland was working normally.
You will need have regular check-ups with your doctor to make sure you are healthy and to spot any signs of the cancer returning.
Question: Will I need follow-up appointments once my thyroid gland has been removed?
Answer: Yes, you will need to have regular tests and check-ups, possibly for several years. These will check that the thyroid cancer has been treated successfully and hasn't returned.
Explanation: You will need to have a blood test four to five months after surgery to remove your thyroid gland to check how much thyroglobulin protein is in your blood. This test will then be repeated every six to 12 months.
Thyroglobulin is produced by a healthy thyroid gland to make thyroid hormones, but it's also produced by papillary or follicular thyroid cancer cells. Once you have had your thyroid gland removed and radioactive iodine has destroyed any remaining cancer cells, your body shouldn't produce any more thyroglobulin. A blood test should show that you have only a very low level of thyroglobulin in your bloodstream, or none at all.
Measuring the change in your thyroglobulin levels over a period of time is more useful than a single blood test. If the blood tests show that your thyroglobulin levels are rising after a thyroidectomy, this may be because you still have some cancer cells in your body. You may be given a radioactive iodine scan to see if any cancer cells are present. After the radioactive iodine scan, you may need further treatment to remove the cancerous or normal thyroid cells.
If the radioactive iodine scan doesn't find any cancer cells, but you still have thyroglobulin in your blood, this may be because the surgery failed to remove all of your healthy thyroid gland cells.
Radioactive iodine scans don't always detect thyroid cells so you may need to have a PET/CT scan. This uses two sorts of imaging at the same time - positron emission tomography (PET) and computerised tomography (CT) - to provide images of your body and detect changes in cells that could be cancerous.
For the PET part, you will be given an injection of a small amount of a radioactive substance (usually a form of sugar) and then the CT uses X-rays and a computer to create detailed images (scans) of the inside of your body.
Question: Do levothyroxine tablets cause side-effects?
Answer: Levothyroxine tablets return your natural hormone levels to a healthy level if your thyroid gland has been removed. They are unlikely to cause side-effects unless you're given too much of the hormone. However, levothyroxine can interact with various other medicines.
Explanation: Side-effects are the unwanted effects of taking a medicine. If you have side-effects, it's important to talk to your doctor or the healthcare professional who prescribed your medicine before you stop taking it.
Thyroxine is a hormone produced by the thyroid gland. It helps your body work at the best pace to keep you in good health. If your thyroid gland has been removed or is underactive, you will no longer produce thyroxine and you will need replacement hormones. Levothyroxine tablets, taken every day, will provide your body with the thyroxine it needs to stay healthy.
Levothyroxine tablets can also prevent papillary or follicular thyroid cancer from coming back, as they stop your body from producing thyroid-stimulating hormone (TSH). TSH usually stimulates the thyroid gland to produce more thyroid hormones, but also encourages thyroid cancer cells to grow.
It's important to take levothyroxine regularly as without it you will develop symptoms of an underactive thyroid gland. These symptoms include gaining weight and feeling cold and tired.
Most people take levothyroxine as a tablet once a day, usually in the morning. The exact dose varies from person to person, but is usually between 50 and 200mcg a day. You may start with a low dose of 25mcg a day). It can take a few months to get the dose right. You will probably have regular check-ups with your GP to make sure you're taking the right dose of thyroid hormone replacement.
As long as the levothyroxine dose is suitable for you, you shouldn't have any side-effects. However, very high doses can cause symptoms such as diarrhoea, being sick, chest pain, muscle cramps and sweating. If you have any of these symptoms, speak to your GP. Reducing the dose should stop these side-effects.
Levothyroxine can interact with other medicines you're taking, for example, warfarin and amiodarone. The amount of levothyroxine getting into your bloodstream may be reduced by antacids (medicines you take for indigestion or heartburn), iron tablets and some other medicines. Always tell your GP or pharmacist if you're taking other medicines while you're taking levothyroxine.
Always ask your doctor for advice and read the patient information leaflet that comes with your medicine.
Question: Will surgery for thyroid cancer affect my voice or cause any other side-effects?
Answer: Surgery to remove all or part of your thyroid gland (thyroidectomy) may cause changes in your voice such as hoarseness. The risk of this being permanent is rare. The level of calcium in your blood may also be low for a short period of time because the parathyroid glands that control this lie near to your thyroid gland and may be bruised during surgery.
Explanation: Your thyroid gland lies just in front of your voice box (larynx) and vocal cords. Sometimes removing your thyroid gland can damage the nerves supplying your voice box. This may make your voice sound hoarse and weak for a few weeks or even months after the operation. You may also find it difficult to make high-pitched sounds, which can affect your singing voice.
These voice problems affect about one in every 250 people who have this operation. In a very small number of people, the voice changes can be permanent.
Your parathyroid glands are small delicate glands found behind your thyroid gland. Sometimes these can get damaged during the operation to remove your thyroid gland.
The parathyroid glands control the level of calcium in your blood. If they are damaged, your calcium levels may fall. This can cause twitching or jerking muscles. You may also feel tingling in some parts of your body, including your hands and fingers.
Low calcium levels affect three out of every 10 people who have a thyroidectomy. Usually low calcium levels are temporary and the parathyroid glands will start working again. However, if a blood test shows that your calcium levels continue to be low, you will probably be prescribed calcium supplements (and sometimes extra vitamin D) until they return to a healthy level.
- Further Information
- Thyroid cancer: risks and causes. Cancer Research UK.www.cancerhelp.org.uk, accessed 30 November 2009
- Types of thyroid cancer. Cancer Research UK.www.cancerhelp.org.uk, accessed 30 November 2009
- The thyroid gland and thyroid cancer. Royal College of Physicians, 2007.www.british-thyroid-association.org
- Thyroid cancer. Macmillan Cancer Support.www.macmillan.org.uk, accessed 30 November 2009
- Thyroid cancer symptoms. Cancer Research UK.www.cancerhelp.org.uk, accessed 30 November 2009
- Guidelines for the management of thyroid cancer. British Thyroid Association and Royal College of Physicians, 2007.www.british-thyroid-association.org
- External radiotherapy. Cancer Research UK.www.cancerhelp.org.uk, accessed 30 November 2009
- Follow-up after treatment for thyroid cancer. Macmillan Cancer Support.www.macmillan.org.uk, accessed 30 November 2009
- UK guidelines for the use of thyroid function tests. British Thyroid Association, 2006.www.british-thyroid-association.org
- Thyroid hormone replacement after surgery for thyroid cancer. Macmillan Cancer Support.www.macmillan.org.uk, accessed 30 November 2009
- Joint Formulary Committee, British National Formulary. 58th ed. London: British Medical Association and Royal Pharmaceutical Society of Great Britain, September 2009
- Hypothyroidism - management. What drug interactions can occur with levothyroxine? Clinical Knowledge Summaries.www.cks.nhs.uk, accessed 30 November 2009
- Life after thyroid surgery. Cancer Research UK.www.cancerhelp.org.uk, accessed 30 November 2009
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