Thyroid Cancer

What is thyroid cancer?

Thyroid cancer refers to cancer that develops within the thyroid, a gland found at the front of the neck. The thyroid produces hormones that help control certain processes in the body such as heart rate, digestion, body temperature and weight.

The thyroid is primarily made up of two types of cells:

  • Follicular cells – these produce and store the hormones T3 and T4 and the protein thyroglobulin (Tg)
  • Parafollicular cells (C-cells) – these produce the hormone calcitonin, which helps control calcium levels in the body

Thyroid cancer is often differentiated by the type of cell the cancer develops from.

The four types of thyroid cancer include:

  • Papillary thyroid cancer – slow-growing cancer that develops from the follicular cells in the thyroid. This is the most common type of thyroid cancer, accounting for 70-80% of all thyroid cancer diagnoses
  • Follicular thyroid cancer – cancer that also develops from the follicular cells in the thyroid. This accounts for 15-20% of all thyroid cancer cases and includes Hürthle cell carcinoma
  • Medullary thyroid cancer – an often hereditary cancer that develops from the parafollicular cells in the thyroid. This accounts for 4-5% of all thyroid cancer diagnoses and can be associated with tumours in other glands
  • Anaplastic thyroid cancer – rare fast-growing cancer that develops from the follicular or parafollicular cells in the thyroid. This accounts for 1-2% of all thyroid cancer cases and typically occurs in people over the age of 60

Thyroid cancer is the ninth most common cancer in Australia, with 3 616 new cases in 2019 (971 new cases in men and 2 645 new cases in women).

Thyroid cancer can appear at any age. Thyroid cancers are three times more frequently diagnosed in women than men. It is the seventh most common cancer affecting Australian women of all ages, and the most common cancer diagnosed in women aged 20 to 24-years-old (the vast majority of them papillary thyroid cancers).

How is thyroid cancer diagnosed?

There are many different tests that are used to diagnose thyroid cancer, alongside a physical examination. This may include blood tests to check for the thyroid hormones levels of T3, T4 and thyroid-stimulating hormone (TSH), an ultrasound to visualise the thyroid, a biopsy (generally a fine needle aspiration (FNA) of the thyroid nodule or enlarged lymph node), or a radioiodine scan. Additional scans may include CT, FDG-PET or MRI scans to detect if the cancer has spread elsewhere.

Stages of thyroid cancer

Thyroid cancer can be described in stages depending on how early or advanced the cancer is.

The TNM system is used to stage thyroid cancer and helps doctors understand what your cancer looks like. TNM stands for:

  • Tumour (T) – describes the size of the primary tumour and any spread of cancer into nearby tissues or structures
  • Node (N) – is a measure of whether the cancer has spread to nearby lymph nodes
  • Metastasis (M) – the degree to which the cancer has spread to other organs or parts of the body

The TNM information, along with other tests helps determine the stage of your thyroid cancer.

Papillary and follicular thyroid cancer (only Stage I and Stage II apply to those under 55 years of age):

  • Stage I – the cancer is no larger than 4 cm and confined to the thyroid. For those under 55, the cancer may be any size and might or might not have spread to nearby lymph nodes.
  • Stage II – the cancer is no larger than 4 cm across and confined to the thyroid, but has spread to nearby lymph nodes. For those under 55, the cancer may be any size and has spread to other areas of the body such as distant lymph nodes, internal organs or bone.
  • Stage III – the cancer may be any size and has spread to nearby tissue such as the larynx, trachea or oesophagus. It might or might not have spread to nearby lymph nodes.
  • Stage IVA – the cancer may be any size and has spread extensively beyond the thyroid toward the spine or into nearby large blood vessels. It might or might not have spread to nearby lymph nodes.
  • Stage IVB – the cancer is any size and might or might not have spread to nearby lymph nodes, but has spread to distant areas of the body such as lymph nodes, internal organs or bones.

Anaplastic thyroid cancer (all anaplastic thyroid cancers are considered Stage IV):

  • Stage IVA – the cancer is any size and confined to the thyroid.
  • Stage IVB – the cancer is any size and confined to the thyroid, but has spread to nearby lymph nodes. Alternatively, the cancer is any size and has grown into the strap muscles around the thyroid, but might or might not have spread to nearby lymph nodes.
  • Stage IVC – the cancer is any size and might or not have spread to nearby lymph nodes, but has spread to distant areas of the body such as lymph nodes, internal organs or bone.

Medullary thyroid cancer:

  • Stage I – the cancer is no larger than 2 cm and confined to the thyroid.
  • Stage II – the cancer is no larger than 4 cm across and confined to the thyroid. Alternatively, the cancer is larger than 4 cm and confined to the thyroid, or any size and growing outside of the thyroid but not involving nearby structures.
  • Stage III – the cancer is any size and may be growing outside of the thyroid but not involving nearby structures. It has spread to lymph nodes in the neck.
  • Stage IVA – the cancer is any size and has grown into nearby tissues in the neck, such as the larynx, trachea or oesophagus. It might or might not have spread to nearby lymph nodes. Alternatively, the cancer is any size and might be growing outside of the thyroid, but has spread to certain lymph nodes in the neck.
  • Stage IVB – the cancer is any size and has grown toward the spine or into nearby large blood vessels, but might or might not have spread to nearby lymph nodes.
  • Stage IVC – the cancer is any size and might have grown into nearby structures or lymph nodes, but has spread to distant areas of the body such as the liver, lung, bone or brain.

Signs and symptoms of thyroid cancer

Thyroid cancer can be difficult to detect as there are often no symptoms during the early stages. However, as the disease progresses symptoms may include:

Lump in the neck or throat

that grows over time

Difficulty swallowing or breathing

Swollen glands

in the neck

Hoarseness or changes in your voice

Pain

in the neck or throat

Treatment for thyroid cancer

Frequently asked questions

What are the risk factors for thyroid cancer?

While the exact causes of thyroid cancer are unknown, factors known to increase the risk of developing thyroid cancer include:

  • Exposure to radiation as a child (e.g. previous radiation therapy treatment) or through living in areas with high radioactive exposure, such as the site of a nuclear disaster (e.g. Chernobyl)
  • Being overweight or obese
  • Having a family history of thyroid cancer associated with the RET gene
  • Pre-existing thyroid conditions such as an enlarged thyroid (goitre) or thyroid nodules
How can thyroid cancer be prevented?

To prevent thyroid cancer, you should consider:

  • Quitting smoking
  • Limiting alcohol intake
  • Having a healthy, balanced diet, with a variety of fruits and vegetables
  • Maintaining a healthy weight

If a family member has been diagnosed with thyroid cancer and you have tested positively for the RET gene mutation, your doctor may discuss preventative treatment such as surgery to remove the thyroid.

References

For a full list of references, click here.
  1. Cancer Council. (2020). Thyroid cancer. Retrieved on 14 April 2021 from https://www.cancer.org.au/cancer-information/types-of-cancer/thyroid-cancer
  2. Cancer Council NSW. (2020). Thyroid cancer. Retrieved on 14 April 2021 from https://www.cancercouncil.com.au/thyroid-cancer/
  3. Clayman, G. (2021). Thyroid Cancer. Retrieved on 14 April 2021 from https://www.endocrineweb.com/conditions/thyroid-cancer/thyroid-cancer#Thyroid_Cancer_Symptoms
  4. Mayo Clinic. (2020). Thyroid cancer. Retrieved 14 April 2021 from https://www.mayoclinic.org/diseases-conditions/thyroid-cancer/symptoms-causes/syc-20354161
  5. American Society of Clinical Oncology. (2021). Thyroid Cancer: Signs and Symptoms. Retrieved on 14 April 2021 from https://www.cancer.net/cancer-types/thyroid-cancer/symptoms-and-signs
  6. The Australian Thyroid Foundation. (2020). Thyroid Cancer. Retrieved on 14 April 2021 from https://thyroidfoundation.org.au/Thyroid-Cancer
  7. healthdirect. (2020). Thyroid cancer. Retrieved on 14 April 2021 from https://www.healthdirect.gov.au/thyroid-cancer
  8. Australian Institute of Health and Welfare. (2019). Cancer in Australia 2019. Retrieved on 14 April 2021 from https://www.aihw.gov.au/reports/cancer/cancer-in-australia-2019/summary
  9. American Cancer Society. (2019). Signs and symptoms of thyroid cancer. Retrieved on 14 April 2021 from https://www.cancer.org/cancer/thyroid-cancer/detection-diagnosis-staging/signs-symptoms.html
  10. American Cancer Society. (2019). Thyroid Cancer Stages. Retrieved on 14 April 2021 from https://www.cancer.org/cancer/thyroid-cancer/detection-diagnosis-staging/staging.html
  11. Cancer Australia. (2020). Thyroid cancer in Australia statistics. Retrieved on 14 April 2021 from https://www.canceraustralia.gov.au/affected-cancer/cancer-types/thyroid-cancer/thyroid-cancer-australia-statistics

Become a patient

Find out how to become a patient at Icon Cancer Centre, or request more information from your nearest centre.
Become a patient

Our doctors

Icon brings together some of Australia’s most experienced medical oncologists, radiation oncologists and haematologists.
Learn more

Care at Icon

At Icon, care is more than just a word. Our cancer care team are here to support you with compassion, knowledge and hope.
Learn more
View all

Search