The thyroid is one of the body’s network of glands. Known as the 'activity' gland, the thyroid produces hormones that are needed to keep the body functioning normally.
- The thyroid gland needs a regular supply of iodine (found in fish, seafood and dairy products) to produce these hormones.
- If the levels these hormones (T3 &T4) in the blood fall, the hypothalamus (part of the brain) sends out thyroid-releasing hormone (TRH) into the blood.
There are 4 main types of cancer of the thyroid:
Lymphoma of the thyroid is also possible, but is fairly uncommon.
What causes thyroid cancer?
The causes of thyroid cancer are unknown, but there are some risk factors:
- A poor diet with large amounts of saturated fat.
- Medullary thyroid cancer may be due to an inherited faulty gene.
- Benign (non-cancerous) thyroid disease can develop into thyroid cancer.
What are the symptoms?
- Lump on the neck
- Difficulty swallowing
Remember: IThese symptoms are common to many illnesses other than thyroid cancer.
How is it Diagnosed?
- Fine-needle aspiration. A biopsy where a small needle is passed gently into the swelling in the neck.
- Blood test. To check the thyroid hormone levels in the blood.
- CT scan
- Thyroid radioisotope scan. A small amount of a slightly radioactive liquid is injected into a vein in the arm. A camera will be positioned over the neck and may be able to show any areas of cancer in the thyroid. The scan itself is painless.
- PET scan. This scan uses low-dose radioactive glucose (a type of sugar) to measure the activity of cells in different parts of the body. Areas of cancer are usually more active than surrounding tissue and show up on the scan.
How is it Treated?
It will depend on the size of the tumour and where it is.
Treatment may involve:
- Surgery – the whole thyroid gland may be removed, not just the tumour. This can mean hormone replacement therapy is required in the future.
- Radioactive Iodine – the cancer cells absorb the iodine and receive a very high dose of radiation.
Surgery for thyroid cancer
The first treatment for cancer of the thyroid is usually surgery. The aim is to remove the tumour – and this may mean that the thyroid gland is partially or totally removed. This depends on the size of the tumour.
Tissues that surround the tumour may also need to be removed depending whether the cancer has spread.
If the thyroid is completely removed the patient will need to take hormones to replace those that are normally produced by the thyroid gland.
Radiotherapy is often given as a follow up to surgery.
Radioactive Iodine for thyroid cancer
Iodine can be used for detection purposes, but when given in larger doses, radioactive iodine can be used to treat any remaining cancer cells after surgery. The thyroid cancer cells absorb the radioactive iodine and receive a very high dose of radiation from it, which destroys them.
This can only be used if there is no healthy thyroid tissue left. It can be taken as capsules or as a drink, or given intravenously.
Because this is such a specific way to treat thyroid cancer, the patient will be radioactive for 4-5 days. This means that they will be in isolation in hospital as the radioactivity is lost from their body through sweat, urine and other body fluids.
Radiotherapy for thyroid cancer
Radiotherapy is given externally to the body and is usually for treatment of medullary or anaplastic thyroid cancer, as they don’t respond as well to radioactive iodine treatment. Sometimes, both radioactive iodine and external radiotherapy will be used together.