What is thyroid cancer?

Thyroid cancer develops when cells in the thyroid gland grow in an abnormal way and divide out of control, forming a tumour. Your thyroid is a small, bow-shaped gland in the front of your neck.

There are different types of thyroid cancer. Some, such as papillary and follicular thyroid cancer are common, but there are also rare types.

Thyroid cancer stages

Thyroid cancer is often categorised into stages according to the TNM (tumour-nodes-metastasis) staging system:

• T (tumour) 0 to 4 — relates to the size of the cancer. The smaller it is, the lower the number.
• N (nodes) 0 or 1 — N0 means no cancer in the lymph nodes, N1 means cancer is in the nodes.
• M (metastasis) 0 or 1 — M0 means the cancer hasn’t spread to other parts of the body, M1 means the cancer has spread.

What are the symptoms of thyroid cancer?

Common types of thyroid cancer often develop slowly and may not cause you obvious symptoms. Some rare forms develop quickly.

When symptoms do occur, they may include:

• a painless lump in the neck or throat
• swelling in the neck
• a hoarse voice
• a cough that doesn’t go away
• difficulty breathing or swallowing

These symptoms can also be caused by other problems. If you notice any of them, don’t assume you have cancer, but do see your doctor as soon as possible.

What causes thyroid cancer?

Doctors don't yet know what causes thyroid cells to become cancerous, but there are some risk factors:

• exposure to radiation
• certain genetic factors
• some thyroid conditions
• living with obesity
• high or low iodine levels

Females are 3 times as likely to develop thyroid cancer than males.

What’s your risk?

Check your cancer risk with Cancer Australia’s calculator.

When should I see my doctor?

See your doctor if you notice changes to your voice, have difficulty breathing or swallowing, notice a swelling in your neck or have a cough that doesn’t go away.

How is thyroid cancer diagnosed?

The diagnosis of thyroid cancer usually involves a physical examination of your neck. Your doctor will refer you for blood tests and imaging such as an ultrasound or CT scan. To confirm if the lump is cancer, you may need a biopsy, so cells from the lump can be check of cancer under the microscope. You may also need a PET scan.

How is thyroid cancer treated?

Most cases of thyroid cancer are treatable and you will often need a combination of treatments.

Surgery

Surgery is the most common treatment for thyroid cancer. Your surgeon may need to remove your entire thyroid gland (total thyroidectomy) or a part of it (partial or hemi-thyroidectomy). Sometimes they will also need to remove nearby lymph nodes.

If you have surgery to remove your whole thyroid you will need to have thyroid hormone replacement therapy for the rest of your life. This makes sure your body gets the important hormones that are usually made by the thyroid. It also reduces the risk of thyroid cancer coming back, because it stops your body from making high levels of hormones which can cause any left-over cancer cells to grow.

Radioactive iodine treatment

Radioactive iodine is a type of medicine used to destroy any cancer remaining after surgery. It is taken up by cancer cells and then kills them without causing much effect to your other cells.

Other treatments

Some people also need chemotherapy, targeted drug therapies, radiotherapy or immunotherapy.

In some cases, if your cancer hasn’t spread outside the thyroid gland and is considered low risk, your doctor may offer you active surveillance. This means your health team will monitoring your cancer closely, rather than having immediate treatment. It usually involves regular ultrasounds and physical examinations.

Are there complications of thyroid cancer and its treatment?

After surgery you may notice changes to your voice, but this is usually temporary. It can also be painful to swallow food in the days after surgery.

The change in hormone levels can affect your mood.

If the surgery affects the parathyroid glands, which are found behind your thyroid, there is a risk that you can have low calcium levels which causes headaches and tingling. This means you will need calcium replacement. Ask your doctor before you start taking supplements for complications of thyroid cancer treatment.

You may have side effects from the chemotherapy, radiotherapy and radioactive iodine therapy such as fatigue and nausea.

If you have radioactive iodine therapy you and your bodily fluids will be radioactive for a few days. This means that you will need to take some precautions to keep the people around you safe. Your health team will guide you on what to do.

Surgery and radioactive iodine treatment don’t usually affect your fertility in the long term.

Resources and support

• Cancer Australia has a detailed booklet all about thyroid cancer.
• Rare Cancers Australia has information about thyroid cancer on their website.
• Head and Neck Cancer Australia has an information video in English and other languages on what to expect after having head and neck cancer treatment.

Aboriginal and Torres Strait Islanders

Cancer Council NSW provides information all about cancer for Aboriginal and/or Torres Strait Islander peoples.

Other languages

General information from Cancer Institute NSW about cancer is available online in many community languages.