Thyroid Cancer 
INTRODUCTION


What is 'Thyroid Cancer'? It is a cancer the affects the thyroid organ in the neck. There are four main types of Thyroid Cancer: Papillary, Follicular, Anaplastic and Medullary. If this is not the cancer type you're looking for, please explore the information about other types of Head and Neck Cancers.


 
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IN THIS SECTION

1. What is Thyroid Cancer?

Cancer occurs when cells become abnormal, grow uncontrollably and have the potential to spread to other parts of the body. These cells build up to form a mass (or lump). 

There are four main types of Thyroid Cancer, most of these come from the follicular cells that make thyroid hormone.

Papillary Thyroid Carcinoma / Cancer

Papillary Thyroid Carcinoma is the most common type of Thyroid Cancer (about 75% of all cases). It tends to grow very slowly, but often spread to lymph nodes. It can be cured or controlled in most people and is rarely fatal.

Follicular Thyroid Carcinoma / Cancer

This accounts for about 5-10% cases. It grows slowly and tends to stay in the thyroid, however it can spread to the lungs or bones if diagnosed late. If diagnosed early, most people with follicular Thyroid Cancer can be treated successfully.

Anaplastic Thyroid Carcinoma / Cancer

This type of Thyroid Cancer is rare (less than 1%) but very aggressive.

Medullary Thyroid Carcinoma / Cancer

This is different from other Thyroid Cancers because they develop in cells called ‘C cells’ that do not produce thyroid hormone. 

There is also Poorly Differentiated Thyroid Cancer, which makes up to 5% of Thyroid Cancer and usually occurs in older people. It can frequently be non iodine-avid.


2. What is the thyroid?

The thyroid gland lies at the base of the neck. It is shaped like a butterfly and wraps around the windpipe (trachea) beneath the voice box (larynx).

The parts of the thyroid are:

  • wings of the butterfly (left and right lobes)

  • body of the butterfly (isthmus, joining the left and right lobes) 

  • there is a small part that lies over the voice-box (pyramidal lobe). 

When the thyroid is larger than normal it is called a goitre. Lumps in the thyroid are called nodules. Most thyroid nodules are benign but some can be cancerous.

Here is a 3D video explainer that explains the thyroid and Thyroid Cancer further:​
 

3. What does the thyroid do?

Glands that release hormones into the blood stream are called endocrine glands, the thyroid is the largest endocrine gland of the body.

The thyroid produces hormones that are released into the blood and carried to every tissue in the body.

There are two types of thyroid hormone, tri-iodothyronine (T3) and thyroxine (T4). These hormones control the speed at which the cells work (metabolism), and are important in brain development and growth in children. These hormones also determine how sensitive other organs are to endocrine hormones. Thyroid hormone is made in cells called follicular cells.

The amount of thyroid hormone in the blood stream is controlled by the pituitary gland. The pituitary gland, is a small endocrine gland that sits under the brain. It releases a hormone into the blood called thyroid stimulating hormone (TSH). When doctors order thyroid tests, they will look at all three of these hormones (T3, T4 and TSH) but TSH is the most important. 

  • Too much thyroid hormone is called hyperthyroidism or an overactive thyroid. This can lead to heart palpitations, trouble sleeping, shaky hands, muscle weakness, nervousness or anxiety, feeling hot and problems with your menstrual periods.

  • ​Not enough thyroid hormone is called hypothyroidism or an underactive thyroid. This can lead to weight gain, lethargy, intolerance to cold weather, depression, constipation and problems with hair loss and dry skin.

Diagram of the thyroid and surrounding areas: 


4. What causes Thyroid Cancer?

Doctors often can’t explain why a person gets cancer. But we do know what makes some cancers more likely.

The two main causes of Thyroid Cancer are: 

  • Being female — In Australia women are about four times more likely than men to get Thyroid Cancer

  • Age — while Thyroid Cancer can occur at any age, it is most common in people aged 40–60 years.

Having a diet low in iodine also increases risk of Thyroid Cancer, but this is rare in Australia as iodine is added to salt and other foods.

Other factors that increase the risk of Thyroid Cancer include: 

  • Radiation — this is a very important risk factor for Thyroid Cancer, either because of medical treatment (particularly low dose radiation treatment in childhood), or from environmental exposure such as atomic explosions or nuclear fallout

  • Having a non-cancerous (benign) thyroid disease — like an enlarged thyroid (goitre), thyroid nodules (adenomas) or inflammation of the thyroid (thyroiditis), or having one of these conditions in your family

  • A family history of Thyroid Cancer or an inherited gene change (mutation) in the RET oncogene (a protein coding gene) 

IN THIS SECTION

1. Introduction to Thyroid Cancer
2. Symptoms, signs and tests of Thyroid Cancer
3. Treatment for Thyroid Cancer

FURTHER INFORMATION
  1. Head and Neck Cancer Australia Resources 
  2. External Links to other Head and Neck Cancer Resources