Thyroid cancer

Thyroid cancer develops when cells of the thyroid grow and divide in an abnormal way. The thyroid is a gland in the neck and is part of the endocrine system.

Thyroid cancer affects almost three times as many women as men and can occur at any age. It is one of the more common cancers diagnosed in younger women.

There are several types of thyroid cancer#

It is possible to have more than one type at once, although this is unusual. Common types include:

• Papillary (about 70 to 80% of cases) – develops from the follicular cells and tends to grow slowly.
• Follicular (about 10%) – also develops from the follicular cells.

Rarer types include:

• Medullary (about 6%) – develops from the parafollicular cells (C-cells). It can run in families and may be associated with tumors in other glands.
• Oncocytic (about 3%) – develops from thyroid follicles. Also known as oxyphilic or Hürthle cell carcinoma.
• Anaplastic (about 1%) – may develop from papillary or follicular thyroid cancer. It tends to grow quickly and usually occurs in people over 60 years old.

Symptoms of thyroid cancer#

Thyroid cancer usually develops slowly, without many obvious symptoms. However, some people experience one or more of the following:

• A painless lump in the neck (the lump may grow gradually).
• Swollen lymph glands (lymph nodes) in the neck, which may slowly grow in size over months or years.
• Trouble swallowing.
• Difficulty breathing.
• Changes to the voice.

Although a painless lump in the neck is a typical sign of thyroid cancer, thyroid lumps are common and turn out to be benign in about 90% of adults. An underactive or overactive thyroid is not typically a sign of thyroid cancer.

Not everyone with these symptoms has thyroid cancer#

If you have any of these symptoms or are worried, always see your doctor.

Some things make it more likely that thyroid cancer will develop. These are called risk factors and they include:

• Exposure to radiation – a small number of thyroid cancers are due to radiation therapy to the head and neck area as a child, or to living in an area with high levels of radiation.
• Family history – only around 5% of thyroid cancers run in families. Some inherited genetic conditions, such as familial adenomatous polyposis or Cowden syndrome, or inheriting the RET gene, may increase your risk.
• Other thyroid conditions – these only slightly increase the chance of developing thyroid cancer.
• Other factors – people who are overweight or obese may have a higher risk.

Having these risk factors does not mean you will develop thyroid cancer. Often there is no clear reason for getting it. If you are worried about your risk factors, ask your doctor for advice.

Tests for thyroid cancer#

Your doctor may do some tests to check for thyroid cancer:

• Ultrasound – to get detailed information about your thyroid, including the size of any nodule and whether it is full of fluid or solid.
• Blood tests – to check your hormone levels and the function of the thyroid. Calcitonin levels may also be checked.
• Biopsy – if you have a thyroid nodule or enlarged lymph node in your neck, you may need a fine needle aspiration (FNA) biopsy to collect a sample of cells and check whether it is cancerous.

Your doctor might ask you to have further tests, which can include:

• CT scan – uses x-rays to take pictures of the inside of your body and compiles them into one detailed cross-sectional picture.
• PET scan – uses an injection of a glucose (sugar) solution to help cancer cells show up more brightly on the scan.

Stages of thyroid cancer#

The stage of a cancer means how far it has grown in your body. In many cases, the information needed for accurate staging is available only after surgery.

The most common way doctors decide on a stage is the TNM system (tumor-nodes-metastasis). This describes whether the cancer is small and remains inside the thyroid or is larger and has spread to other parts of the neck, whether it has spread to nearby lymph nodes, and whether it has spread to other parts of the body, such as the lungs or bones. Ask your doctor or nurse to explain the stage of the cancer.

Prognosis and survival rates#

When someone is diagnosed with thyroid cancer, their doctor will give them a prognosis – an opinion of how likely the cancer is to spread and the chances of getting better. A prognosis depends on the type and stage of cancer, test results and a person’s age, fitness and medical history.

The most common types of thyroid cancer have an excellent long-term prognosis, especially if the cancer is found only in the thyroid or nearby lymph nodes in the neck. Even if the cancer has spread, the outcome can still be good.

Doctors commonly use 5-year survival rates to discuss prognosis. This is because research studies often follow people for 5 years – it does not mean you will survive for only 5 years. Thyroid cancer has a very high 5-year survival rate (around 97%). Your doctor will talk to you about your individual situation when working out your prognosis.

Treatment for thyroid cancer#

The type of treatment your doctor recommends will depend on the type and stage of the thyroid cancer, and your age and general health.

Active surveillance

Your doctor may recommend closely monitoring the cancer rather than treating it straightaway. This is known as active surveillance and usually involves regular ultrasounds and physical examinations. There is good evidence that it is safe for small papillary thyroid cancers where there is no sign the cancer has spread.

Some people choose active surveillance if treatment side effects would affect their quality of life more than the cancer itself. Others find it makes them anxious and prefer treatment straightaway. Treatment can be considered at any stage if you change your mind or if the cancer grows or spreads.

Surgery

Surgery is the most common treatment. You will usually be given a general anesthetic, and the surgeon will make a small cut (about 5 to 7 cm) across your neck. How much tissue is removed depends on how far the cancer has spread:

• Partial thyroidectomy – only the affected lobe or section of the thyroid is removed.
• Total thyroidectomy – removal of the whole thyroid. Most people with thyroid cancer need this.
• Lymph node removal – nearby lymph nodes may also be removed.
• Other tissue – in very rare cases, the surgeon removes other affected tissue near the thyroid.

Thyroid hormone replacement therapy

Many people who have a partial thyroidectomy will not need hormone replacement, because the remaining lobe continues to make enough hormones. After the whole thyroid is removed, your body no longer produces the hormones that maintain your metabolism, so you will be prescribed a hormone tablet. Taking thyroid hormone tablets keeps your metabolism working at a normal, healthy rate and reduces the risk of the cancer coming back.

Radioactive iodine (RAI)

RAI is a type of radioisotope treatment, given as a pill that you swallow. Although it spreads through the body, it is mainly absorbed by thyroid cells or thyroid cancer cells, which it kills while leaving other body cells relatively unharmed.

RAI may be used to destroy tiny amounts of cancer cells or healthy thyroid tissue left behind after surgery. It is usually recommended for papillary or follicular thyroid cancers that have spread to the lymph nodes or have a higher risk of returning. RAI is generally not given until some weeks after surgery, once swelling has gone down, because swelling can affect blood flow and stop the RAI circulating well. You will need to stay in hospital for about 36 to 48 hours in an isolated room to safely contain the radioactivity.

Targeted therapy

Targeted therapy drugs attack specific features of cancer cells to stop the cancer growing and spreading. The most common drugs used for thyroid cancer are tyrosine kinase inhibitors (TKIs). If you have advanced thyroid cancer that has not responded to RAI, you may be offered a TKI such as lenvatinib, taken as a daily tablet. Other TKIs may be available through clinical trials.

External beam radiation therapy (EBRT)

EBRT uses a controlled dose of radiation to kill cancer cells or damage them so they cannot grow, multiply or spread. Most people with thyroid cancer do not need EBRT, but it may be recommended in particular circumstances, such as:

• After surgery and RAI if the cancer has not been completely removed or there is a high risk of recurrence.
• As palliative treatment to relieve symptoms such as pain caused by cancer that has spread.
• To help control medullary or anaplastic thyroid cancer, because these types do not respond to RAI.

Radiation therapy is usually given 5 days a week over several weeks. You may be fitted for a plastic mask to wear during treatment, which helps you stay still so the radiation is targeted at the same area each session.

Chemotherapy and immunotherapy

Chemotherapy is not often used for thyroid cancer, but it may treat advanced cancer that is not responding to RAI or targeted therapy, or be combined with radiation therapy to treat anaplastic thyroid cancer. The drugs are usually given by injection into a vein, and the number and length of sessions varies from person to person. Immunotherapy uses the body’s own immune system to fight cancer. Talk to your specialist to find out more about new treatments and clinical trials.

Side effects of treatment#

All cancer treatments can have side effects. Your treatment team will discuss these with you before you start. Talk to your doctor or nurse about any side effects you experience. Some can be upsetting and difficult, but help is available.

Managing lifestyle changes#

Fertility

Many people diagnosed with thyroid cancer are under 40 and may worry about how treatment will affect their ability to have children. Fertility is usually not permanently affected by surgery or radioactive iodine treatment.

In the short term, it is recommended that you delay trying to conceive for about 6 months after treatment. RAI may have a short-term effect on eggs and sperm, so you will be advised to use contraception for a set amount of time. If you or your partner want to have a baby after RAI, talk to your doctor. Women also need to check that their thyroid hormone levels are normal before trying to get pregnant.

Sexuality and body image

Having thyroid cancer and treatment can change the way you feel about yourself, other people, relationships and sex. These changes can be very upsetting and hard to talk about. Doctors and nurses are very understanding and can give you support. You can also ask for a referral to a counselor or therapist who specializes in body image, sex and relationships.

Living with advanced cancer#

Advanced cancer usually means cancer that is unlikely to be cured. Most people with thyroid cancer respond well to treatment and do not need palliative care services. However, people at any stage of advanced thyroid cancer may benefit from palliative treatment.

Many people think palliative care is only for people who are dying, but it is for any stage of advanced cancer. There are doctors, nurses and other professionals who specialize in it. Most people continue to have treatment for advanced cancer as part of palliative care, as it helps manage the cancer and improve day-to-day life. Treatment may include chemotherapy, radiation therapy or another type of treatment, and it can:

• Slow down how fast the cancer is growing.
• Shrink the cancer.
• Help you live more comfortably by managing symptoms, such as pain.

Treatment depends on your preferences and what you want to do. Ask your doctor about treatment and palliative care services that may help you.

Support for carers, family and friends#

Caring for someone with cancer can be difficult at times. If you are caring for someone with thyroid cancer, talk to their care team about support services, and ask your doctor or nurse about local or national cancer support and carer support organizations.

Key points#

• Thyroid cancer usually develops slowly, without many obvious symptoms.
• Not everyone with these symptoms has thyroid cancer.
• If you have any of these symptoms or are worried, always see your doctor.
• Some people, such as those with certain risk factors, may have a higher risk of developing thyroid cancer.
• Having these risk factors does not mean you will develop thyroid cancer.

Where to get help#