Thyroid cancer is a rare type of cancer that affects the thyroid gland, a small gland at the base of the neck that produces hormones.

It's most common in people in their 30s and those over the age of 60. Women are two to three times more likely to develop it than men.

Thyroid cancer is usually treatable and in many cases can be cured completely, although it can sometimes come back after treatment.

This section covers:

Symptoms of thyroid cancer

Symptoms of thyroid cancer can include:

  • a painless lump or swelling in the front of the neck – although only 1 in 20 neck lumps are cancer
  • swollen glands in the neck
  • unexplained hoarseness that doesn't get better after a few weeks
  • sore throat that doesn't get better
  • difficulty swallowing

Read more about the symptoms of thyroid cancer.

When to get medical advice

See your GP if you have symptoms of thyroid cancer. The symptoms can be caused by less serious causes, such as an enlarged thyroid (goitre), so it's important to get them checked out.

Your GP will examine your neck and can organise a blood test to check how well your thyroid is working.

If they think you could have cancer or they're not sure what's causing your symptoms, you'll be referred to a hospital specialist for more tests.

Read more about how thyroid cancer is diagnosed.

Types of thyroid cancer

There are four main types of thyroid cancer:

  • papillary carcinoma – the most common type, accounting for about 8 in 10 cases; it usually affects people under 40, particularly women
  • follicular carcinoma – accounts for up to 1 in 10 cases and tends to affect middle-aged adults, particularly women
  • medullary thyroid carcinoma – accounts for less than 1 in 10 cases; unlike the other types, it can run in families
  • anaplastic thyroid carcinoma – the rarest and most serious type, accounting for around 1 in 50 cases; it usually affects people over the age of 60

Papillary and follicular carcinomas are sometimes known as differentiated thyroid cancers. They tend to be easier to treat than the other types.

Causes of thyroid cancer

Thyroid cancer occurs when a change to the DNA in the cells in the thyroid causes them to grow uncontrollably and produce a lump.

It's not usually clear what causes this, but there are a number of things that can increase your risk.

These include:

  • other thyroid conditions, such as an inflamed thyroid (thyroiditis) or goitre – but not an overactive thyroid or underactive thyroid
  • a family history of thyroid cancer – your risk is higher if a close relative has had thyroid cancer
  • radiation exposure in childhood – such as radiotherapy
  • obesity
  • a bowel condition called familial adenomatous polyposis (FAP)
  • acromegaly – a rare condition where the body produces too much growth hormone

Treatments for thyroid cancer

Treatment for thyroid cancer depends on the type of thyroid cancer you have and how far it has spread.

The main treatments are:

  • surgery – to remove part or all of the thyroid
  • radioactive iodine treatment – you swallow a radioactive substance that travels through your blood and kills the cancer cells
  • external radiotherapy – a machine is used to direct beams of radiation at the cancer cells to kill them
  • chemotherapy and targeted therapies – medications used to kill cancer cells

After treatment, you'll be advised to have regular appointments to check whether the cancer has come back.

Read more about how thyroid cancer is treated.

Outlook for thyroid cancer

Overall, the outlook for thyroid cancer is good. Around 9 in every 10 people are alive five years after diagnosis. Many of these are cured and will have a normal lifespan.

But the outlook varies depending on the type of thyroid cancer and how early it was diagnosed.

For example:

  • more than 9 in 10 people with papillary carcinoma live at least five years after diagnosis
  • more than 8 in 10 people with follicular carcinoma live at least five years after diagnosis
  • around 6 or 7 in 10 people with medullary thyroid carcinoma live at least five years after diagnosis
  • fewer than 1 in 10 people with anaplastic thyroid carcinoma live at least five years after diagnosis

The cancer comes back in another part of the body, such as the lungs or bones, in up to one in four people treated for thyroid cancer. But it can often be treated again if this happens.

^^ Back to top


The main symptom of thyroid cancer is a lump in the front of the neck.

But thyroid cancer tends to develop slowly and there may not be any symptoms at first.

Neck lump

Thyroid cancer often causes a painless lump or swelling low down in the front of the neck.

However, neck lumps are common and are usually caused by a less serious condition, such as an enlarged thyroid (goitre). Only around 1 in every 20 is cancer.

A neck lump is more likely to be cancer if it:

  • feels firm
  • doesn't move around easily under the skin
  • gets bigger over time

See your GP if you have a swelling or lump at the front of your neck. While it's unlikely to be cancer, it's important to get it checked out.

Other symptoms

Other symptoms of thyroid cancer include:

Rarely, thyroid cancer can affect the production of thyroid hormones and cause diarrhoea and flushing.

These problems can have causes other than cancer, but it's a good idea to see your GP if you develop any persistent symptoms that you're worried about.

^^ Back to top


It's a good idea to see your GP if you have possible symptoms of thyroid cancer.

Your GP will examine your neck and ask about any other symptoms you may be experiencing, such as unexplained hoarseness.

If they think you might have a thyroid problem, they may arrange some tests or refer you to a hospital specialist.

The tests you may have are described below.

Blood test

blood test known as a thyroid function test is used to check the levels of thyroid hormones in your blood.

Abnormal levels could mean that you have an overactive thyroid or an underactive thyroid, rather than cancer.

Further tests, such as an ultrasound scan, will be needed if the test shows that your thyroid gland is working normally.

Ultrasound scan

An ultrasound scan is a type of scan that uses sound waves to create an image of the inside of your body. It's the type of scan used during pregnancy to check on the baby.

An ultrasound scan of your neck can be used to check for a lump in your thyroid that could be caused by cancer.

If a potentially cancerous lump is found, a biopsy will be carried out to confirm the diagnosis.


The only way to be sure whether a lump on the thyroid is cancer is to remove a small sample of cells from it and study them under a microscope. This is known as a biopsy.

This is usually done using a thin needle inserted into the lump. An ultrasound scan may be carried out at the same time to ensure the needle goes into the right place.

The procedure is usually carried out as an outpatient procedure, which means you won't have to spend the night in hospital.

Further tests

If a biopsy finds that you have thyroid cancer, further tests may be needed to check whether the cancer had spread to another part of your body.

The main two tests used for this are:

Stages of thyroid cancer

After you're diagnosed with thyroid cancer, it will be possible to give your cancer a stage. This is a number that indicates how far the cancer has spread.

Doctors use a system called the TNM system to stage thyroid cancer. This consists of three numbers:

  • T (tumour) – given from 1 to 4, depending on the size of the tumour
  • N (node) – given as either 0 or 1, depending on whether the cancer has spread to nearby lymph glands
  • M (metastases) – given as either 0 or 1, depending on whether the cancer has spread to another part of the body

Knowing the stage of your cancer will help your doctors decide on the best treatment for you.

The Cancer Research UK website has more detailed information about the TNM staging system for thyroid cancer.

^^ Back to top


Treatment for thyroid cancer depends on the type of thyroid cancer you have and how far it has spread.

The main treatments are:

You'll also need continuing care after treatment to check for and prevent any further problems.

Your treatment plan

You'll be cared for throughout your treatment by a team of healthcare professionals. Your team will recommend what they feel is the best treatment for you.

This will largely depend on the type of thyroid cancer you have. For example:

  • papillary carcinoma and follicular carcinoma can usually be treated with surgery followed by radioactive iodine treatment
  • medullary thyroid carcinoma is usually treated with surgery to remove the thyroid, often followed by radiotherapy
  • anaplastic thyroid carcinoma can't usually be treated with surgery, but radiotherapy and chemotherapy can help control the symptoms

You may want to write down a list of questions to ask your team before you go to hospital to discuss your treatment options.


Surgery is the first treatment for most types of thyroid cancer. It may involve removing:

  • part of the thyroid
  • the whole thyroid
  • nearby lymph glands

The operation is carried out under a general anaesthetic, where you're asleep. Most people are well enough to leave hospital after a few days.

You'll need to rest at home for a few weeks and avoid any activities that could put a strain on your neck, such as heavy lifting. You'll have a small scar on your neck, but this should become less noticeable over time.

It's a good idea to talk to your surgeon about the exact operation they recommend and find out what it involves.

Radioactive iodine treatment

A course of radioactive iodine treatment is often recommended after surgery. This will help destroy any remaining cancer cells in your body and reduce the risk of the cancer returning.

Preparing for treatment

An iodine-rich diet may reduce the effectiveness of radioactive iodine treatment, so you'll be advised to follow a low-iodine diet for a week or two before treatment begins.

It's recommended that you:

  • avoid all seafood
  • limit the amount of dairy products you eat
  • don't take cough medicines – these can contain iodine
  • eat plenty of fresh meat, fresh fruit and vegetables, pasta and rice

Tell your care team if you think you could be pregnant, as the treatment isn't safe during pregnancy.

Women should avoid getting pregnant for at least six months afterwards, and men should avoid fathering a child for at least four months.

If you're breastfeeding, you'll ideally need to stop for at least eight weeks before treatment starts.

You should avoid breastfeeding your current child after treatment, but you can safely breastfeed any babies you may have in the future.

The procedure

Radioactive iodine treatment involves swallowing radioactive iodine in either liquid or capsule form. The iodine travels through your blood and kills any cancerous cells.

You'll need to stay in hospital for a few days afterwards because the iodine will make your body slightly radioactive. As a precaution, you'll need to stay in a single room and won't be able to have visitors at first.

You'll be able to have visitors and go home once the radiation levels in your body have come down. Your care team will advise you whether you need to take any precautions after going home.

Side effects

Side effects of radioactive iodine treatment are uncommon, but can include:

  • neck pain or swelling
  • feeling sick
  • a dry mouth
  • an unpleasant taste in the mouth

The treatment doesn't affect fertility in women. Fertility can be reduced in men after treatment, but it should improve over time.

External radiotherapy

External radiotherapy may be used to reduce the risk of thyroid cancer coming back after surgery if radioactive iodine treatment isn't suitable or is ineffective.

It can also be used to control symptoms of advanced or anaplastic thyroid carcinomas if they can't be fully removed with surgery.

External radiotherapy usually involves treatment once a day from Monday to Friday, with a break at weekends, for four to six weeks.

Side effects of radiotherapy can include:

  • feeling and being sick
  • tiredness
  • pain when swallowing
  • a dry mouth

These side effects should pass within a few weeks of treatment finishing.

Chemotherapy and targeted therapies

Chemotherapy is rarely used for thyroid cancer nowadays, but it's sometimes used to treat anaplastic thyroid carcinomas that have spread to other parts of the body.

It involves taking powerful medicines that kill cancerous cells. It doesn't cure thyroid cancer, but may help control the symptoms.

More recently, newer medicines known as targeted therapies have been used more widely to treat several types of thyroid cancer.

These specifically target cancer cells, rather than harming healthy cells at the same time as chemotherapy does.

Targeted therapies still aren't offered routinely on the NHS, but may be available in special circumstances. The decision about whether to fund treatment with medications used in targeted therapies is often made by individual Health Boards.

Alternatively, your care team may suggest taking part in a clinical trial studying targeted therapies for thyroid cancer.

After treatment

After your treatment has finished you may need to continue taking medication to reduce the risk of further problems.

You'll also be advised to have regular check-ups to look for signs of the cancer coming back.

Medication and supplements

If some or all of your thyroid gland is removed, it will no longer produce thyroid hormones.

This means you'll need to take replacement hormone tablets for the rest of your life to prevent symptoms of an underactive thyroid, such as fatigue, weight gain and dry skin.

Occasionally, the parathyroid glands can be affected during surgery. These glands are located close to the thyroid gland and help regulate the levels of calcium in your blood.

If your parathyroid glands are affected, your calcium levels may temporarily decrease. If this happens, you might need to take calcium supplements until the glands start to function normally again.

Follow-up tests

Thyroid cancer can come back after treatment, so you'll be asked to attend regular check-ups to look for signs of this.

You may need tests every few months to begin with, but they'll be needed less frequently over time.

Tests you may have include:

  • a blood test – to detect substances released by cancerous thyroid cells
  • an ultrasound scan – to check for signs of cancer in your neck
  • a radioisotope scan – a type of scan that highlights cancerous thyroid cells

Treatment will usually need to be repeated if your cancer does come back.

^^ Back to top

The information on this page has been adapted by NHS Wales from original content supplied by NHS Choices.
Last Updated: 29/09/2016 08:45:22