Thyroid cancer

About thyroid cancer

Thyroid cancer happens when abnormal cells grow uncontrollably, and form a lump or tumour. There are different types of thyroid cancer. Some grow slowly and others grow quickly.

The thyroid is a butterfly-shaped gland found that sits at the front of the throat. It has two halves, called lobes. These two lobes sit on either side of the windpipe (trachea), just below the voice box (larynx).

The thyroid is part of the endocrine system, which is a group of glands that makes and controls the body’s hormones.

The thyroid has different types of cells that make hormones to control your metabolic rate, including your heart rate, how fast you digest food, your body temperature and weight. These hormones are called T4 and T3.

There are 2 main types of cells in the thyroid:

• Follicular cells – These cells make and store the hormones T4 and T3, and make a protein called thyroglobulin (Tg).
• Parafollicular cells (C-cells) – These cells make the hormone calcitonin.

About 4,300 people are diagnosed with thyroid cancer each year in Australia, and rates are increasing. Women are more than twice as likely to develop thyroid cancer as men. Although it is the most common type of cancer that affects women aged 20–24, most of the people diagnosed with thyroid cancer are women in their 40s, 50s and 60s, and men in their 50s, 60s and 70s.

Types of thyroid cancer

There are different types of thyroid cancer. Some grow slowly and others grow quickly. In rare cases, you can have more than one type of thyroid cancer at once. Common types of thyroid cancer include:

• Papillary (about 80% of all thyroid cancer cells) – develops from the follicular cells and tends to grow slowly.
• Follicular (about 10%) – develops from the follicular cells.

Rarer types of thyroid cancer include:

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

Symptoms of thyroid cancer

Thyroid cancer usually develops slowly, without obvious signs, but symptoms may include:

• a lump or nodule in the neck (usually painless, may grow gradually)
• swelling in the neck
• trouble swallowing
• difficulty breathing
• changes to the voice (e.g. hoarseness that doesn’t go away)
• swollen lymph nodes in the neck (may grow slowly over months or years)
• a cough that doesn’t go away.

Although a painless lump in the neck is a typical sign of thyroid cancer, most of the time this is not a thyroid cancer. Having 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.

Risk factors for thyroid cancer

The exact cause of most thyroid cancers is not known, but some things may increase your risk.

• Radiation exposure - thyroid cancer usually takes 10–20 years to develop after significant radiation exposure. A small number of thyroid cancers may be from the following:
  • radiation therapy to the head or neck as a child
  • living in an area with high levels of radiation
  • radiation exposure at work (e.g. medical or military).
• Family history - About 5% of thyroid cancers are linked to a family history. Having a parent, child or sibling with papillary thyroid cancer, or an inherited genetic condition, such as familial adenomatous polyposis (FAP) or Cowden syndrome, may increase your risk. Some people inherit a faulty gene, the RET gene, that can cause familial medullary thyroid cancer (FMTC) or the thyroid condition multiple endocrine neoplasia (MEN).
• Thyroid conditions - Having thyroid nodules, an enlarged thyroid (called a goitre) or inflammation of the thyroid (thyroiditis) only slightly increases your chance of developing thyroid cancer.

Having these risk factors doesn’t mean you will develop thyroid cancer. 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:

• Blood tests – to check your hormone levels and function of the thyroid. Calcitonin levels may also be checked.
• Ultrasound – to get detailed information about your thyroid including the size of any thyroid nodule and whether it is full of fluid or solid. Can also show if nearby lymph nodes may be affected.
• 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. It can be difficult to tell if follicular tumours are cancerous from an FNA, so a surgical biopsy may be needed to check this.
• Genomic tests – These blood or tissue tests look for changes (mutations) in the genes. These tests are not often needed for thyroid cancer, however your doctor may suggest these tests if they suspect medullary thyroid cancer or certain cancers that need targeted therapy.

Your doctor might ask you to have further tests. These can include:

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

Stages of thyroid cancer

Staging describes the size of the cancer and how far it may have spread. It may not be possible to know the stage until after surgery.

The cancer is usually classified as low, intermediate or high risk. You may be given an idea of what to expect (prognosis), based on the cancer type, how advanced it is, and if it has spread.

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.

Most people will have a combination of surgery, thyroid hormone replacement therapy and, sometimes, RAI treatment. Less often, people may also have targeted therapy, radiation therapy or chemotherapy.

Active surveillance

Some people may not need treatment right away. This is called active surveillance, and means having regular ultrasounds and check-ups.

• It is usually only for small papillary thyroid cancers that haven’t spread, or small, low-risk cancers.
• It may also be used after partial thyroidectomy surgery when only part of the thyroid remains.
• Some people choose active surveillance if treatment side effects would make them feel worse than the cancer itself.
• A specialist thyroid radiologist will need to map the tumour. If this shows that the cancer is close to muscle, the vocal nerve, windpipe or oesophagus, you will usually need to have surgery.
• Your doctor will explain changes to watch out for.
• You can usually start treatment later if you change your mind, or the cancer grows or spreads.

Surgery

Surgery is the most common treatment for thyroid cancer. You will be given a general anaesthetic, and the surgeon will make a small cut (3 to 5 cm) across your neck.

How much tissue is removed will depend on how far the cancer has spread:

• Partial thyroidectomy – only the affected lobe or section of the thyroid is removed.
• Total thyroidectomy – many people with thyroid cancer need to have a total thyroidectomy. This involves removing the whole thyroid, both lobes and the isthmus.
• Lymph node removal – nearby lymph nodes may also be removed.

Thyroid hormone replacement therapy

When the whole thyroid is removed, your body can’t make enough T4 (thyroxine) hormone. You’ll need to take tablets for the rest of your life to keep a healthy metabolism and reduce the risk of cancer returning. This is because T4 stops your pituitary gland releasing too much thyroid-stimulating hormone (TSH), which can help thyroid cancer grow.

If there’s a high risk of cancer returning, you will take a high dose of T4 – called TSH suppression. To find the right dose, you’ll have blood tests every 6–8 weeks to begin with. A small number of people experience side effects at first, including anxiety, problems sleeping, racing heart and sweating.

Radioactive iodine treatment

Also called radioactive iodine ablation or thyroid ablation, this treatment destroys any remaining cancer cells and thyroid tissue left after surgery. It uses radioactive iodine (RAI) or I-131 that you take as a tablet in hospital. RAI kills thyroid cells and thyroid cancer cells while having little effect on other body cells. You have RAI treatment weeks or months after surgery, when any swelling has gone down.

RAI is used for:

• papillary, follicular or oncocytic cancer
• cancer that has spread to lymph nodes
• cancer with a high risk of coming back

RAI is not used for:

• for medullary or anaplastic thyroid cancers (which don’t take up iodine)
• if you are pregnant or breastfeeding (RAI will be done at a later time)

External beam radiation therapy

External beam radiation therapy (EBRT) is only suggested for thyroid cancer that has a high risk of coming back. It may be used if surgery hasn’t removed all the cancer near important structures such as the windpipe. EBRT may be used for medullary or anaplastic thyroid cancers (which do not respond to RAI). Rarely, it is used as palliative treatment – to relieve symptoms if the cancer has spread.

EBRT directs high-energy radiation beams precisely to the affected area, to kill cancer cells or damage them so they cannot grow, multiply or spread.

Other treatments

Most thyroid cancers respond well to common treatments, but a small number may need other options or newer treatments.

Targeted therapy

This drug treatment attacks specific features of cancer cells, to stop the cancer growing and spreading. It is given as a daily tablet, which you take for several years. Targeted therapy may be suggested if RAI treatment isn’t working. It may also be available on clinical trials for rare or aggressive thyroid cancers.

Chemotherapy

This may be used in combination with radiation therapy to treat anaplastic thyroid cancer or when advanced thyroid cancer has not responded to RAI treatment or targeted therapy. Chemotherapy is given by injection into a vein (intravenously), with the number of sessions and length of treatment varying from person to person.

Immunotherapy

This is a drug treatment that uses the body’s own immune system to fight cancer. It’s not commonly used for most thyroid cancers, but may be available through clinical trials for anaplastic thyroid cancer.

Radiopeptide therapy

This radioactive nuclear medicine may be available through clinical trials for advanced medullary thyroid cancer. A protein (peptide) combined with a small amount of radioactive substance (radionuclide) is given intravenously, through a needle into a vein. It targets cancer cells and delivers a high dose of radiation that kills or damages them. It is also called peptide receptor radionuclide therapy (PRRT).

Clinical trials

Over the years, clinical trials have improved treatments and led to better outcomes for people diagnosed with cancer.

Talk with your doctor about the latest clinical trials and whether you’re a suitable candidate.

You can also search for cancer trials available in Victoria through the Victorian Cancer Trials Link.

Side effects of thyroid cancer treatment

All cancer treatments can have side effects. Your treatment team will discuss these with you before you start treatment. Talk to your doctor or nurse about any side effects you are experiencing. Some side effects can be upsetting and difficult, but there is help if you need it. Call Cancer Council Tel. 13 11 20 or contact cancer support to speak with a qualified professional.

Managing lifestyle changes from thyroid cancer

Fertility concerns

If you or your partner want to have a baby after RAI treatment, talk to your doctor. RAI may have a short-term effect on eggs and sperm, so you’ll be advised to delay pregnancy for 6 months after treatment. Women also need to check that their thyroid hormone levels are normal before trying to get pregnant.

Sexuality

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 ask for a referral to a counsellor or therapist who specialises in body image, sex and relationships.

Living with advanced cancer

Advanced cancer usually can’t be cured, but it can often be controlled. Palliative care is person-centred care that helps people with a progressive life-limiting illness to live as fully and comfortable as possible.

Many people are reluctant to use palliative care because they think it is just for people who are dying, but it is useful at all stages of advanced cancer. It also provides support to families and carers.

Depending on your needs, you may use palliative care services occasionally or continuously for a few weeks or months.

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 sometimes. If you are caring for someone with thyroid cancer, these organisations can help:

• Cancer Council – Information and support line Tel. 13 11 20 (or 13 14 50 for an interpreter)
• Carer Gateway Tel. 1800 422 737
• Carers Australia Tel. 1800 422 737

Where to get help

• Your GP (doctor)
• Cancer Council
  • Information and support line Tel. 13 11 20 (or 13 14 50 for an interpreter)
  • Understanding thyroid cancer
  • Podcasts
  • Fertility
  • Sex and intimacy
  • Cancer Council Victoria, My Cancer Guide - Find support services that are right for you.
• Nurse-On-Call Tel. 1300 606 024
• The Australian Thyroid Foundation Tel. 0447 834 724
• Australian and New Zealand Endocrine Surgeons