Thyroid cancer

This section is about thyroid cancer. There are different types of thyroid cancer. It is important to remember that thyroid cancer can often be successfully treated. Most young people are completely cured.

Young woman

The thyroid

The thyroid is a small gland in the front of the neck, just below the voicebox (larynx). It is made up of two parts (or lobes), one on each side of the neck. 

The thyroid gland is part of a network of glands throughout the body that make up the endocrine system. This system makes hormones in the body. Hormones help control and influence different functions in the body. 

These hormones are:

  • thyroid hormone - this controls your metabolism
  • calcitonin - this helps to control the calcium levels in your body.

Types of thyroid cancer

There are four main types of thyroid cancer:  

  • Papillary is the most common type of thyroid cancer. It is usually slow-growing
  • Follicular is a less common type. It is also usually slow-growing
  • Medullary is a rare type of thyroid cancer. It sometimes
  • Anaplastic is another rare type of thyroid cancer. It usually affects older people.

Papillary and follicular thyroid cancer are the most common types in teenagers and young adults.

Rarely, other types of cancer are found in the thyroid gland. For example, lymphoma or other cancers that have spread from another part of the body. 

Symptoms of thyroid cancer

The first symptom of thyroid cancer is usually a painless lump or swelling in the front of the neck that gradually gets bigger.  

Less common symptoms are:  

  • a hoarse voice that doesn't get better  
  • difficulty swallowing or breathing  
  • swollen glands (lymph nodes) in your neck. 

If you have any of these symptoms, it is important to see your GP. They will be able to talk to you about your symptoms. If they think the symptoms could be because of cancer, they can arrange some tests to find out more. 

Remember, these symptoms can happen for lots of reasons other than cancer.

Causes of thyroid cancer

We don’t know exactly what causes thyroid cancer, but research is looking into this.  

Some things called risk factors increase your chance of developing cancer. But having these does not mean you will get cancer. The main risk factors for thyroid cancer are: 

Family history 

Your risk of developing thyroid cancer is increased if you have a close relative (parent, brother, sister or child) with thyroid cancer. Even with this, your risk is still quite small because thyroid cancer is rare. 


Genes are the biological information in each cell that we inherit from our parents. Genes affect the way we look (for example, our eye colour) and how our bodies grow and work. Some rare genetic conditions that run in families can increase the risk of thyroid cancer. But fewer than 1 in 10 cases of cancer are caused by an inherited faulty gene.  


If you were exposed to radiation or had radiotherapy to the neck when you were younger, you may have a higher risk of developing thyroid cancer many years later.  

Having tests for thyroid cancer

You may have tests at your GP surgery or at the hospital. The tests will help your doctors see whether you have thyroid cancer.

Visiting your GP  

If you think you might have symptoms of thyroid cancer, you should go to your GP. They will be able to talk to you about your symptoms, and will usually examine you. 

There may be different reasons why you have these symptoms. To find the cause, your GP will arrange some blood tests and make an appointment for you with a specialist at the hospital. 

If there is a chance you could be pregnant, please tell your doctor. 

At the hospital  

If you need more tests, you will be referred to a hospital. This could be a general hospital or a specialist cancer hospital.  

You will probably see lots of different healthcare professionals at the hospital. They will work together to find out the cause of your symptoms and to plan your care.  

You might see: 

  • a doctor who specialises in thyroid problems (endocrinologist) 
  • a surgeon who specialises in thyroid surgery  
  • a pathologist who studies cells and looks at biopsies 
  • a doctor who is an expert in cancer (oncologist)  
  • a doctor who is trained to look at x-rays and scans (radiologist) 
  • a specialist nurse. 

Your specialist doctor (endocrinologist) will examine you and arrange for more tests. These may include: 

  • An ultrasound scan – this scan uses sound waves to build up a picture of the part of the body being scanned. 
  • A fine needle aspiration (FNA) – this test involves having a very small needle placed into your thyroid gland to remove a few cells. The pathologist will look at these cells under the microscope. This test is not usually painful. 
  • A biopsy – this is when your doctor takes a small piece of tissue from a part of your body to look at it closely.   

Further tests

If the tests show that you have thyroid cancer, you may have more tests to check the size of the tumour and whether it has spread. Sometimes the tests may be done after .

The tests include:

  • a chest x-ray to check your lungs
  • a CT, MRI or PET scan
  • a radioisotope scan.

You probably won’t need all of these tests. Having tests and waiting for the results can be a difficult time. Talking about how you feel and getting support from your family, friends, specialist nurse or doctor can help.

More information about tests and scans

Treatment for thyroid cancer

It is important to remember that thyroid cancer can often be successfully treated. Most people are completely cured. If the tests showed that you have thyroid cancer, your healthcare team will discuss treatment with you. 


You can read about what happens before and after an operation in our general information about surgery.  

Surgery to remove the whole thyroid gland is the main treatment for thyroid cancer. This operation is called a thyroidectomy

Sometimes the surgeon will only need to remove the lobe of the thyroid that contains the cancer. This is called a lobectomy.

You may feel shocked and scared about having surgery. Your doctor and nurse will tell you more about it so that you know what to expect. 

Try to remember that surgery is usually a very successful treatment for thyroid cancer. 

We have more information about what happens when you go into hospital for an operation in the surgery section. 

Lymph nodes 

There are lymph nodes in the neck, close to the thyroid. These are part of the body’s immune system and help fight infection. The lymph nodes might contain cells that could become cancerous in the future. So sometimes, the surgeon might also remove some, or all, of the nodes. They may also remove some tissue from around the thyroid if they think it might contain cancer cells. 

After the operation

After your operation, the nurses on the ward will help you to lie in an upright position, supported by pillows. This helps to reduce swelling in your neck area. 

You might have a low calcium level in your blood after the operation. This is because there is a small risk that surgery will damage the parathyroid glands. These are four very small glands behind the thyroid gland. They produce parathyroid hormone, which helps to control the level of calcium in your blood. The nurses will test your blood to check the calcium level.

You may have a hoarse voice after the operation. This is because the thyroid gland is near the nerves that control your vocal cords. These nerves can be bruised or damaged during surgery. This can make your voice sound hoarse and weak. Your doctor might check your vocal cords before and after the surgery.

You will probably need to spend one or two days in hospital after the operation. There will be a scar on your neck, usually just above the collarbone. It might look quite red at first, but will fade over time.

You may need to take tablets to replace the thyroid hormone. There is more information about thyroid hormone replacement therapy below. 

The tissue that was removed during the operation will be looked at under a microscope. The results will help your doctors decide if you need more treatment. This could be another operation, radioactive iodine treatment or other treatments. Your doctor will explain the results of the operation to you.

If you want to know more about what happens when you have an operation, there is more information in the general surgery section. 

Hormone therapy after surgery for thyroid cancer

What happens after surgery?

If you have had the whole of your thyroid gland removed, your body won’t be able to produce thyroid hormones anymore. Without these hormones, your metabolism slows down. This can cause:  

  • tiredness, weakness and lack of energy 
  • poor concentration 
  • constipation 
  • feeling cold 
  • a low mood  
  • dry skin and hair. 

What can help?

Thyroid hormones can be replaced by taking tablets. You will need to take them for the rest of your life. The most common long-term hormone replacement tablet is thyroxine (levothyroxine). 

If you need to have radioactive iodine treatment, you might be given a different type of thyroid hormone. It is taken until the iodine treatment is finished, and then usually replaced with thyroxine. 

As well as replacing the missing hormones, thyroxine can also help stop some types of thyroid cancer coming back. Some people are given the thyroid hormone tablets as part of your on-going cancer treatment.

Blood tests

You will need to have your blood checked regularly to monitor the hormone levels. It can sometimes take months to find the right dose of thyroxine for you. But when the right dose is found, you should not have any side effects. This is because they are just replacing normal thyroid hormones. 

Remember to take your tablets every day. It can help to take them at the same time every day so you get into a routine. 

Radioactive iodine treatment

Radioactive iodine is a type of radioisotope treatment that targets thyroid cells. Radioisotopes are radioactive substances given by mouth as a drink or capsules, or injected into a vein. 

It is usually given: 

  • to destroy any remaining thyroid tissue in the neck after an operation – this is called radioiodine remnant ablation (RRA)
  • to treat any thyroid cancer cells that were not removed with surgery
  • to treat thyroid cancer that has come back after initial treatment.

Normally, the thyroid gland takes up (absorbs) iodine from our diet and uses it to make thyroid hormones. When you have radioactive iodine, the thyroid cells absorb the iodine and receive a very high dose of radiation. This destroys the thyroid cells and any cancer cells that may remain after surgery. 

Radioactive iodine does not usually affect other parts of the body because other cells don’t absorb iodine the way thyroid cells do. 

You can’t have this treatment if you are pregnant. If there is any chance of this, tell your healthcare team and they can test you.

How radioactive iodine treatment is given

You usually have radioactive iodine as a capsule. Sometimes it is given as a drink or as an injection into a vein in your arm through a cannula. 

Taking thyroid hormones before treatment

Radioactive iodine treatment does not work if you are taking thyroid hormone replacement tablets. To prepare your body for the treatment, you will need to stop taking your thyroid hormone tablets for 2 to 4 weeks. While you are not taking the thyroid hormones, you will have symptoms of low thyroid hormone, such as tiredness and lack of energy, poor concentration and constipation. 

These symptoms should stop when you start taking thyroid hormone tablets again, but it can take some time.

Sometimes, instead of having to stop taking the hormone tablets, you are given two injections of a drug called thyrotropin alfa (Thyrogen®). Having this injection means you can keep taking your hormone replacement tablets, so you will not get the symptoms of low thyroid hormone. Thyrotropin is not suitable for everyone. Your doctor or specialist nurse can tell you if you can have this treatment.

Some people won’t start taking thyroid hormones until after radioactive iodine treatment. 

Having a low iodine diet before treatment

For one or two weeks before radioactive iodine treatment, you will be asked to eat a low-iodine diet and avoid certain foods. This encourages the body to use up its stores of iodine. Having a very low amount of iodine in the body means that when the radioactive iodine is given, any remaining cancer or thyroid cells will absorb it. This can help make the treatment more effective. 

You will be given information about a low-iodine diet. 

During treatment 

Radioactive iodine treatment makes you radioactive for a few weeks. Your body will gradually get rid of the radioactivity through your wee, sweat and saliva. You will be kept in hospital when the radioactivity is highest, which is usually a few days. You will be looked after in a side room on the ward. 

During this treatment, the amount of contact you can have with family, friends, and your healthcare team will be limited. This is to protect them from exposure to the radiation. Anyone who is pregnant or younger than 18 is not usually allowed to visit. 

You will be able to keep in touch with your family and friends by phone, text and the internet. There may be books, magazines, DVDs, computer games or a TV in the room. You can take in some of your own things to help pass the time. Ask your team whether you can take your computer, tablet or phone into the room with you. Anything that comes back out of your room will be checked for radiation levels. Sometimes your things may have to be kept on the ward for a few days if the radiation levels are high. But they will be returned to you when they are safe again. 

After treatment 

Once your radiation levels are safe, you will be allowed to go home. Check with the staff about what you can and can’t do when you get home. There will probably be some precautions you will need to take for a few weeks. 

You will have a scan shortly after your treatment. This will help show the doctors if you need more radioactive iodine treatment. If you need more treatment, it is usually given after six months.

Your fertility won’t be affected by the treatment. But you should not become pregnant for six months, or make someone pregnant for four months, after radioactive iodine treatment. You should also avoid all sex and open-mouthed kissing for a few days after treatment.

After treatment, you might set off the alarms at the airport security gates for up to six months. If you are planning a holiday, discuss it with your healthcare team.

External beam radiotherapy

Some people have external beam radiotherapy, but it is used much less often than radioactive iodine treatment. External beam radiotherapy uses high-energy rays to destroy cancer cells. The rays are given from outside the body. 

Radiotherapy is usually given as an outpatient. But sometimes you might be in hospital while you have it. You normally have radiotherapy as a series of short treatment sessions of about 10 to 20 minutes. You will have treatment Monday to Friday, with a rest at the weekend.

During the radiotherapy, you will need to lie still on a narrow bed that is under a radiotherapy machine. Radiotherapy machines are quite big, and look like large x-ray machines.

Radiotherapy is like having an x-ray, so it does not hurt and you cannot feel it. 

More information about radiotherapy

Follow-up tests

After your treatment is finished, you will see the doctor and have regular tests to monitor your condition.

Thyroglobulin test

Thyroglobulin is a protein that is normally made by the thyroid cells. It can also be made by some types of thyroid cancer cells. Levels of thyroglobulin can be detected in the blood, so you will have regular thyroglobulin blood tests.

After treatment there should not be any thyroglobulin in the body. It would only be found in your blood if a small amount of thyroid tissue is left, or if some thyroid cancer cells remain in your body. This means the thyroglobulin blood test is a useful way of detecting any remaining cancer cells. 

Stimulated thyroglobulin test

This test is done 9 to 12 months after having radioactive iodine treatment. It is used to see if you need any more radioactive iodine treatment. 

You may need to stop taking your thyroid hormone replacement a few weeks before the blood test. Your doctor or specialist nurse will give you information about this.

Ultrasound scan of the neck

You may have regular ultrasound scans of your neck.

Radioactive iodine scan

You may have a radioactive iodine scan a few months after treatment. This is to check whether there are any thyroid cancer cells in your body. Your doctor or nurse will give you more detailed information about this test if you need to have it.

Other scans

If your thyroglobulin level is raised, or your scans show any abnormal areas, you may have further tests. These may include:

  • MRI (magnetic resonance imaging) scan
  • CT (computerised tomography) scan
  • PET-CT (positron emission tomography) scan.

More about tests and scans

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Based on content originally produced by Macmillan Cancer Support.