- In 2021, it’s estimated that 3,830 Australians were diagnosed with thyroid cancer. This makes thyroid cancer the 9th most commonly diagnosed cancer in Australia
- Thyroid cancer is more common in women than in men. In 2021, women were two and half times more likely to develop thyroid cancer
- The five-year survival rate for thyroid cancer is 97%
- Thyroid cancer primarily develops from two types of cells: follicular cells (which produce and store the hormones T3 and T4 and the protein thyroglobulin) and parafollicular cells (which produce the hormone calcitonin and help control calcium levels in the body)
Thyroid cancer develops when cells grow and divide abnormally in the thyroid, a small butterfly-shaped gland at the front of the neck.
Thyroid cancer is classified based on the appearance of its cancerous cells. It is possible to have multiple types of thyroid cancer, however this is rare.
The types of thyroid cancer include:
Papillary thyroid cancer
Papillary thyroid cancer is the most common type of thyroid cancer, making up 70-80% of all cases. It develops from the follicular cells and tends to grow slowly to areas such as surrounding lymph nodes.
Follicular thyroid cancer
Follicular thyroid cancer makes up 15-25% of thyroid cancer cases and develops from follicular cells. Although it is unlikely to spread to the lymph nodes, it can spread to other parts of the body. Hürthle cell carcinoma is a rare and more aggressive type of follicular thyroid cancer.
Medullary thyroid cancer
Medullary thyroid cancer develops from the parafollicular cells (C-cells) and makes up 4% of all thyroid cancer cases. It can be passed down through families (hereditary thyroid cancer).
Anaplastic thyroid cancer
Anaplastic thyroid cancer is a rare and fast-growing type of thyroid cancer, which develops from papillary or follicular thyroid cancer.
As signs and symptoms for thyroid cancer can be similar to other common conditions, it’s important to see your GP or healthcare professional if you experience any of the symptoms below. Discussing anything concerning with your doctor as soon as possible can help give you peace of mind and offer the best chance of successful treatment if you receive a thyroid cancer diagnosis.
Symptoms for thyroid cancer tend to develop slowly and may include:
Lump in the neck or throat that grows over time
Pain in the neck or throat
Difficulty swallowing or breathing
Hoarseness or changes in your voice
Swollen glands (lymph nodes) in your neck
The TNM system is used to stage thyroid cancer and helps doctors understand what your cancer looks like. The TNM stands for:
- Tumour – Describes the size of the tumour and if it has affected other tissue, such as the neck
- Node – Is a measure of whether lymph nodes have been affected
- Metastasis – The degree to which the cancer has spread to other organs of the body, such as the lungs or bones
The TNM information, along with other tests, helps determine the stage of your thyroid cancer using the guidelines below:
Papillary and follicular thyroid cancer
Only Stage I and Stage II apply to those under 55 years of age.
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.
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.
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.
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.
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.
The cancer is any size and confined to the thyroid.
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.
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
The cancer is no larger than 2 cm and confined to the thyroid.
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.
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.
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.
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.
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.
Approximately 5% of thyroid cancer cases are related to family history. Inherited genetic conditions such as familial adenomatous polyposis or Cowden syndrome can increase your risk of papillary thyroid cancer.
While a majority of people with medullary thyroid cancer do not have a family history of the disease, medullary thyroid cancer can be caused by inheriting a faulty gene called the RET gene. Inherited medullary thyroid cancer is called familial medullary thyroid carcinoma (FMTC). This faulty gene can also result in multiple endocrine neoplasia (MEN).
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 anywhere else within the body.
The cause of thyroid cancer is not fully known, however there are some factors which contribute to the risk of thyroid cancer developing, including:
- Gender – Women are more likely to develop thyroid cancer than men
- Certain life-style related factors – Such as being overweight
- Family history – Including a family history of a faulty gene called the RET gene
- Exposure to high levels of radiation – Such as from childhood radiation therapy treatment
- Having non-cancerous (benign) thyroid disease – Including Hashimoto’s disease (a condition where the immune system attacks the thyroid), enlarged thyroid (goitre), thyroid nodules and inflammation of the thyroid (thyroiditis)
In 2021, there is an estimated 1 in 83 risk of being diagnosed with thyroid cancer by the age of 85. With over 70% of these cases in 2021 being found in women, women’s risk is higher at 1 in 58.
There are a number of lifestyle-related factors that can reduce your risk of developing thyroid cancer, like:
- Getting regular exercise – Cancer Australia recommends at least 30 minutes of moderate-intensity exercise each day
- Eating a healthy, balanced diet – Eat a fibre-rich diet from grain and legume sources, as well as enjoy a variety of fruit (2 serves) and vegetables (5 serves) per day, limit your intake of salt, saturated fats, and avoid all processed meat
- Limiting alcohol intake
- 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.
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- Cancer Council. (2020). Understanding Thyroid Cancer: A guide for people with cancer, their families and friends. Retrieved on 5 January 2022 from https://www.cancer.org.au/assets/pdf/understanding-thyroid-cancer-booklet
- Cancer Australia. (2021). Thyroid cancer in Australia statistics. Retrieved on 5 January 2022 from https://www.canceraustralia.gov.au/cancer-types/thyroid-cancer/statistics
- American Cancer Society. (2019). What Causes Thyroid Cancer? Retrieved on 5 January 2022 from https://www.cancer.org/cancer/thyroid-cancer/causes-risks-prevention/what-causes.html
- American Cancer Society. (2020). Thyroid Cancer Risk Factors. Retrieved on 5 January 2022 from https://www.cancer.org/cancer/thyroid-cancer/causes-risks-prevention/risk-factors.html
- American Cancer Society. (2019). Can Thyroid Cancer Be Prevented? Retrieved on 5 January 2022 from https://www.cancer.org/cancer/thyroid-cancer/causes-risks-prevention/prevention.html
- Cancer Research UK. (2021). Thyroid Cancer. Retrieved on 5 January 2022 from https://www.cancerresearchuk.org/about-cancer/thyroid-cancer
- Better Health Channel. (2021). Thyroid Cancer. Retrieved on 5 January 2022 from https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/thyroid-cancer
- The Australian Thyroid Foundation LTD. (2021). Thyroid Cancer. Retrieved on 5 January 2022 from https://thyroidfoundation.org.au/Thyroid-Cancer
- Australian Institute of Health and Welfare. (2021). Cancer data in Australia. Retrieved on 5 January 2021 from https://www.aihw.gov.au/reports/cancer/cancer-data-in-australia/contents/cancer-summary-data-visualisation
- National Cancer Institute. (2021). Thyroid Cancer—Patient Version. Retrieved on 5 January 2021 from https://www.cancer.gov/types/thyroid
- 11. Mayo Clinic. (2020). Thyroid Cancer. Retrieved on 5 January 2022 from https://www.mayoclinic.org/diseases-conditions/thyroid-cancer/symptoms-causes/syc-20354161
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