Alternative names for thyroid cancer
Papillary carcinoma of the thyroid; follicular carcinoma of the thyroid; medullary carcinoma of the thyroid; hurtle cell carcinoma of the thyroid; anaplastic thyroid cancer.
What is thyroid cancer?
Lumps (nodules) can sometimes appear on the thyroid gland. These are made of an overgrowth of cells and are usually benign. However, sometimes the lump is made up of cells that continue to grow in an unrestricted way that may eventually invade structures next to the thyroid or spread to other parts of the body. These are known as cancerous cells and the nodules as thyroid cancer.
Occasionally cancer from another part of the body can spread to the thyroid and lymph node cancer, known as lymphoma, can also develop in the thyroid.
What causes thyroid cancer?
In most patients the reason for the cancer starting is never discovered. It is a little more common in patients who have a pre-existing thyroid condition such as a multinodular goitre or Hashimoto’s thyroiditis, but most thyroid cancers appear as a single nodule in the thyroid.
If the thyroid has been exposed to radiation in the past, this increases the risk of benign nodules as well as thyroid cancer. Some specialists recommend that patients who have had radiotherapy to the neck as a treatment for blood or lymphoma should have regular thyroid checks. The small doses of radiation in normal X-rays of the neck or in radioactive iodine used to treat an overactive thyroid do not seem to lead to an increased risk of cancer.
Some families have more members with thyroid cancer than would normally be expected by chance, but this is very rare.
What are the signs and symptoms of thyroid cancer?
Most patients with thyroid cancer will first visit their doctor when they discover a lump in the neck in the region of the thyroid gland. If a GP thinks that the lump might be a thyroid cancer, an urgent appointment at a specialist clinic is made available within two weeks under the NHS rules.
How long the lump has been present is not a very good guide to whether or not it is cancer. Sometimes thyroid cancers can cause uncomfortable swelling in the neck or affect the voice. If the cancer spreads to nearby lymph nodes, these may be felt as well. Thankfully, most patients with these symptoms turn out not to have thyroid cancer, but they all need to be investigated. Sometimes the only way to be certain whether a thyroid lump is cancerous is to remove the part of the thyroid which contains the lump for examination. This is called a biopsy.
Sometimes thyroid cancer is detected by chance when a patient has a scan for an unrelated reason.
How common is thyroid cancer?
Thyroid cancer itself is very rare in the UK. The quoted lifetime risk for women of developing thyroid cancer is one in 324 and for men one in 842. This amounts roughly to four per 100,000 people as of 2007. According to research, 2100 patients in the UK were newly diagnosed with thyroid cancer in 2007. Women are three times more likely than men to be affected.
Is thyroid cancer inherited?
In a very small number of families, more cancers are found than would normally be expected by chance. In some cases an abnormal gene can be found. Medullary thyroid cancer can also be associated with cancerous or non-cancerous lumps (tumours) in other endocrine glands, particularly the adrenal glands which sit near the top of the kidneys.
How is thyroid cancer diagnosed?
Most tests are carried out as an outpatient. The doctor will examine the patient and take blood tests to assess how well the thyroid is functioning. Thyroid cancer can happen with a normal or underactive thyroid and sometimes with an overactive thyroid.
The patient may have an ultrasound scan to look at the thyroid and the adjacent lymph nodes and will almost certainly have some form of needle test. Most doctors use a small needle (the same as for blood tests) to remove some thyroid cells from the gland which are then examined under a microscope. The test might sound frightening but, in fact, usually hurts even less than a simple blood test. The result can take a few days to be returned.
If the doctor cannot confidently rule out thyroid cancer, the test might need to be repeated. If a conclusion still cannot be made, the side of the thyroid containing the suspicious lump can be removed under general anaesthetic (thyroidectomy). Before this, most patients also have a check-up to make sure that the nerves to the voice box are working normally.
How is thyroid cancer treated?
Thyroid cancer is quite rare and generally has a very good outlook. The treatment will be planned taking into account which type of thyroid cancer the patient has, how far the cancer has spread, the patient’s age, general health and level of fitness. The treatment options which may be considered include surgery and radioactive iodine therapy. All specialists agree that, wherever possible, the first step is surgical removal of the cancer and any lymph nodes in the neck that might be involved.
Depending on the type and size of the cancer, it may not be necessary to remove the whole of the thyroid. However, most patients have the whole gland removed (total thyroidectomy) usually at a second operation through the same scar. The team of doctors will then discuss what was found at the operation in detail and make suggestions about what other treatment might be helpful. Sometimes further scans are required at this stage.
The most common recommendations are for radioactive iodine treatment and sufficient doses of thyroid medication to keep a hormone called thyroid stimulating hormone at very low levels in the blood. Treatment with radioactive iodine requires a few days’ stay in hospital and there are usually some restrictions on how much time the patient can spend near other people, particularly children, for a period of time after they leave hospital.
Are there any side-effects to the treatment?
All surgery carries some risks but, although serious complications from thyroid surgery are rare, it is important that the patient has them explained in detail by the surgeon. Changes in the quality of the voice are usually very small and only a problem for people who use their voice professionally. More significant voice change, which makes the voice very weak, usually recovers over time. If they have any concerns, they should ask their doctor.
The radioactive iodine therapy does not affect the ability to have children in men or women, but a delay is necessary after the treatment before starting to try for pregnancy. It does not make hair fall out or affect body weight.
What are the longer-term implications of thyroid cancer?
Patients treated for thyroid cancer usually have a blood test every year and in some cases regular scans are recommended. Most patients will be taking thyroxine tablets for life. Unless there have been any complications from surgery, patients usually return to all their previous activities.
Written: March 2011. Review due: March 2013