What is thyroid cancer?
Thyroid cancer is when abnormal cells in the thyroid gland start to divide and grow in an uncontrolled way. Without treatment, cancer cells can eventually grow into surrounding healthy tissues. They may spread to other areas of the body.
The thyroid gland sits in the throat. This 2 minute video describes the different parts of the throat.
We call this area the throat but in fact it includes a number of different parts. The thyroid gland, trachea, nasopharynx, oropharynx, larynx and the oesophagus.
At the top of the throat is the nasopharynx or the back of the nose. When we breathe in air passes through the nasopharynx into the lungs.
The next part of the throat is the oropharynx or the back of the mouth. It includes the soft palate, the back wall of the throat, the tonsils and the back part of the tongue.
The larynx, or the voice box, is the part of the throat that contains the epiglottis and the vocal cords. As we breathe in air passes through the vocal cords to make sound. When we swallow the epiglottis closes to prevent food and liquid entering the airway, allowing the food to pass into the oesophagus or food pipe.
Surrounding the larynx is the hypopharynx and on either side of the larynx are the piriform sinuses. They help to channel food into the oesophagus.
The trachea or windpipe starts in the throat area. It is the tube that air moves through as air passes in and out of the lungs.
The thyroid gland sits just below the larynx in front of the trachea. It makes hormones that help the body to work normally.
The parathyroid glands are just behind the thyroid gland. They help control the amount of calcium in the body.
And finally, there are lymph glands throughout this part of the body. Our lymph glands are part of our immune system and help us to fight infections.
For more information about cancers that start in the throat and symptoms of throat cancer go to cruk.org/throat
The thyroid gland
The thyroid is a small butterfly shaped gland that makes and releases hormones. It’s found at the front of your neck in the lowest part, just behind the small hollow where your collar bones meet. You can’t usually feel a thyroid gland that is normal.
The thyroid gland is in 2 halves called lobes. They connect together with a thinner bridge of thyroid tissue. The bridge is called the isthmus.
A thyroid cancer is usually found in just one lobe. But some types of thyroid cancer can be found in both lobes.
What does the thyroid gland do?
The thyroid gland is part of the endocrine system. It makes hormones which affect the way your body works. It makes 3 hormones:
- T3 (tri iodothyronine)
- T4 (thyroxine)
- Calcitonin
T3 and T4
T3 and T4 help to control how fast your body works. This is your metabolic rate.
If you don’t make enough T3 and T4 hormones
Your body cells work slower than usual. You might put on weight, feel very tired and lack in energy. This is called hypothyroidism or having an underactive thyroid.
If you make too many T3 and T4 hormones
Your body cells work faster than usual. You can lose weight, despite an increased appetite. You might also feel anxious and find it difficult to relax. This is called hyperthyroidism or an overactive thyroid.
What is thyroid stimulating hormone (TSH)?
The pituitary gland is at the base of your brain and is also part of the endocrine system. It senses when the levels of T3 and T4 are too low and releases thyroid stimulating hormone (TSH). TSH stimulates the thyroid gland to produce more T3 and T4. If the pituitary gland senses that levels of T3 and T4 are too high, it stops making TSH. So the thyroid makes less T3 and T4.
Calcitonin
The thyroid gland produces another hormone called calcitonin. It helps to control the amount of calcium circulating in the blood. Calcitonin works with a hormone called parathyroid hormone to do this.
The parathyroid glands make parathyroid hormone. These sit behind and are attached to the thyroid gland.
Too much calcium can make you feel sick and drowsy. Too little can cause nerve problems, such as pins and needles, making muscles twitch and jerk.
Your surgeon leaves the parathyroid glands behind if they remove your thyroid gland. But the operation can affect them and they may take a while to get back to normal. Your doctor will check your calcium levels regularly and might give you calcium supplements.
Where does thyroid cancer start?
There are 2 main types of cell in the thyroid gland. These are:
- follicular cells
- C cells, that make calcitonin
Less common cells include immune system cells (lymphocytes) and supportive cells (stromal cells).
There are different types of thyroid cancer. The type you have depends on what type of cell the cancer starts in. Some growths and tumours in the thyroid gland can be non cancerous (benign), and others are cancerous (malignant).
Most thyroid cancers start in follicular cells. This includes:
- papillary thyroid cancer
- follicular thyroid cancer
- oncocytic (hurthle cell) thyroid cancer
A small number of thyroid cancers start in the C cells. These are called medullary thyroid cancers.
How common is thyroid cancer?
Thyroid cancer is quite rare. Around 3,900 people are diagnosed in the UK each year. It’s more common in women than in men.
There are factors that can increase the risk of developing thyroid cancer. These include radiation and some types of non cancerous thyroid conditions.
