Cancer Types
Thyroid Cancer
Information about thyroid cancer.
What is thyroid cancer?
The thyroid is a butterfly shaped gland that sits at the front of the neck. It produces hormones:
- T3 and T4 - important in controlling your body’s metabolism
- Calcitonin - involved in controlling your calcium levels
Cancer can start in the ‘follicular cells’ that produce and store T3 and T4 (follicular or papillary thyroid cancer) or from the ‘parafollicular cells’ that produce calcitonin (medullary thyroid cancer). Another form of thyroid cancer is called anaplastic and this is quite rare.
The most common is papillary thyroid cancer which makes up about 80% of all thyroid cancers.
Who can be affected by thyroid cancer?
Thyroid cancer can occur at any age and it affects women far more than men. The number of thyroid cancers detected has increased but some of this is because radiological imaging (e.g. ultrasound scans) has improved leading to the detection of smaller often insignificant thyroid cancers.
Thyroid cancer is more common among Pacific people in New Zealand.
Risk factors
Anything that can increase your risk is called a risk factor. Having one or more of these risk factors does not mean that you will develop thyroid cancer. Even if you have no risk factors you could still develop thyroid cancer.
Personal factors
- Radiation exposure
- Family history
- Inherited genetic conditions e.g. familial adenomatous polyposis (FAP), Cowden syndrome, multiple endocrine neoplasia (MEN)
- Obesity
- Thyroid inflammation (thyroiditis)
- Goitre
Signs and symptoms
Thyroid cancers usually develop slowly without any obvious symptoms. The following signs and symptoms can be experienced but they also occur in conditions that are not thyroid cancer.
- Painless lump in the neck
- Trouble swallowing or breathing
- Change to the voice e.g. hoarseness
- Swollen glands (lymph nodes) in the neck
A thyroid lump may be a sign of a cancer but thyroid lumps are very common and are not usually cancerous. An under-active or over-active thyroid is not a symptom of cancer.
Diagnosis
Examination of the thyroid involves feeling your neck for the size and firmness of the thyroid, and to identify any enlarged lymph nodes.
Blood tests are not used to diagnose thyroid cancer but help to determine if the thyroid is working normally. Tests are likely to include levels of T3, T4, TSH (hormone that stimulates your thyroid) and calcium. Thyroglobulin (a protein produced by the thyroid gland related to T3 and T4), calcitonin and CEA (a type of tumour marker) may be measured as these can be useful for monitoring your body's response to treatment or if your cancer returns after treatment.
An ultrasound will be performed because this helps determine if any lumps felt are solid or filled with fluid. Solid lumps are more likely to be cancerous. The ultrasound can also be used as a guide to obtain a biopsy of a lump (taking a small amount of tissue to look at under the microscope) if it is too small to be felt.
A biopsy called a fine needle aspiration (FNA) is usually performed, cells are taken from the thyroid lump using a fine needle and then are looked at by a pathologist.
Other investigations sometimes used are CT, MRI and PET scans and laryngoscopy, an examination of your vocal cords.
Treatment
If you are suspected to have thyroid cancer, you will be referred to a surgical specialist. Both general surgeons and Ear Nose and Throat Surgeons are trained to treat thyroid cancer.
The treatment for thyroid cancer depends on the results of the biopsy, the type of thyroid cancer you have, your symptoms and your preferences.
Surgery usually involves complete removal of the thyroid gland. For follicular and papillary thyroid cancers, surgery can be followed by radioactive iodine treatment especially if the cancer has spread to the lymph nodes or further. There is no role for radioactive iodine with medullary thyroid cancer – if this has spread radiation therapy may be used instead.
The most common thyroid cancers have excellent long-term survival. Survival is based on many factors but the 5-year survival for thyroid cancer is 98%.
Helpful websites
Australian and New Zealand Head and Neck Cancer Society
Australian and New Zealand Endocrine Surgeons