Thyroid cancer Mate pukupuku o te repe tenga

Your thyroid gland is found in the lower front of your neck. It produces thyroid hormones, which are important in controlling your body's metabolism — helping your body use energy and stay warm. They also keep your brain, heart, muscles and other organs working as they should.

It is not known what causes most thyroid cancer. It is more common in people who:

• have had their thyroid gland exposed to radiation
• have a family history of thyroid cancer
• have an enlarged thyroid (goitre) or inflammation of the thyroid
• are very overweight
• are older than 45.

Thyroid cancer affects women far more than men, and it is more common among Pacific people.

Routine x-rays (such as dental x-rays, chest x-rays and mammograms) do not cause thyroid cancer.

The first sign of thyroid cancer is usually a painless lump (nodule) in your thyroid. But most thyroid lumps are not caused by cancer.

Thyroid nodules

Other symptoms include:

• difficulty swallowing or breathing
• changes to your voice such as hoarseness
• swollen glands (lymph nodes ) in your neck.

Your healthcare provider will ask you questions about your symptoms and examine your neck. They will arrange a blood test to check your thyroid function .

You will also have a scan of your thyroid.

Radionuclide thyroid scan

To confirm if a nodule is thyroid cancer you will need to have a sample taken called a fine needle aspirate (FNA) or have it removed during surgery.

You may need further blood tests and scans such as a CT, MRI or PET scan.

If you have thyroid cancer, it may be one of several types.   

Types of thyroid cancer

Papillary thyroid cancer

This is the most common type and makes up about 80% of all thyroid cancers. It can happen at any age and tends to grow slowly, spreading first to the lymph glands in your neck. It usually has an excellent outlook even after it has spread to the lymph nodes.

Follicular thyroid cancer

This type makes up about 15% of all thyroid cancers. It tends to affect people aged from 40 to 60. Follicular thyroid cancer can grow into the lymph nodes in the neck. It may also grow into blood vessels and then spread to other parts of the body, such as the lungs and bones.

Follicular thyroid cancer can usually be cured, even if it has spread.

Medullary thyroid cancer

Medullary thyroid cancer accounts for about 5% of all thyroid cancers. It is more likely to run in families and may be associated with other hormone problems. It may also be associated with a faulty gene. In these cases, a blood test can screen family members for the gene defect (called a RET mutation).

Medullary thyroid cancer can usually be cured.  

Poorly differentiated thyroid cancer

Poorly differentiated thyroid cancer has cancer cells that have more abnormalities and look less like normal cancer cells than other cancers. It is uncommon but it is aggressive and more difficult to treat.

Anaplastic thyroid cancer

This is the most severe and aggressive form of thyroid cancer. It grows quickly, is unpredictable and difficult to treat. It is a very rare form of thyroid cancer. 

Surgery

Surgery is the main treatment for all thyroid cancer.

Usually, the surgeon removes all the thyroid gland, or as much of it as possible. After surgery, you will need to take thyroid hormones for the rest of your life.

Surgery often cures the thyroid cancer, especially if the tumour is small.

Radioiodine treatment

You might need to have radioiodine to destroy any thyroid or thyroid cancer cells that are left, especially if:

• the cancer is large
• it has spread to your lymph nodes
• there is a high risk your cancer will come back.

Papillary and follicular thyroid cancers can usually be cured with surgery and radioiodine treatment. Radioiodine is very effective as it can seek out and destroy thyroid cancer cells without damaging other tissues in your body.

Radioiodine is safe and has few side effects.

Radioiodine treatment

After you have finished your treatment, you will need regular health checks because thyroid cancer returns in 10 to 20% of people — sometimes many years after treatment. 

These follow-up checks will include a physical examination and blood tests. Blood tests will check your thyroid hormone levels and measure thyroglobulin (a protein produced by your thyroid gland), and can indicate if the cancer has returned.

Your healthcare provider might also arrange an ultrasound scan of your neck to look for any sign the cancer has returned.