Key Facts
Thyroid cancer is the 18th most common cancer in women but is much less common in men.
The number of new thyroid cancers has increased over the past 25 years and varies considerably from country to country.
Germany has three times more new cases of thyroid cancer each year than the UK whilst France has twice as many cases as the UK. However, it is Iceland that has more cases than any other nation in Europe.
Most thyroid cancers can be treated effectively, although they can recur.
Early diagnosis means simpler treatment and better results.
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Key Figures
| Total number of new cancer cases in Europe (2006) |
3.2 million |
| Total number of cancer deaths in Europe (2006) |
1.7 million |
| Number of new thyroid cancer cases |
c. 25,000 per year (Europe) |
| Number of thyroid cancer deaths (2006) |
c. 6,000 per year (Europe) |
Differentiated thyroid carcinomas (papillary and follicular types) have the best prognosis (10-yr survival in excess of 90%).
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Cancer Types
There are four different types of thyroid cancer:
- Papillary carcinoma - the most common, accounting for about 75 - 85% of all cases, and occurs mainly in younger women.
- Follicular cancer - affects slightly older people but is less common than papillary carcinoma and accounts for about 10 - 15% of all cases. Hürthle cell cancer (less than 5% of all cases) is a particular form of follicular cancer that tends to grow more rapidly than other cancers of this type.
- Medullary carcinoma - this is rare (less than 5% of all thyroid cancers) and sometimes hereditary.
- Anaplastic carcinoma - also uncommon, accounting for less than 5% of all cases across Europe. However, there are big differences from country to country.
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Causes of Thyroid Cancer
Thyroid cancer is three times more common in women.
It is most common in people aged between 20 and 60.
Asian people are more prone to developing thyroid cancer.
Follicular cancers are more common where diets are low in iodine, which is an essential ingredient of thyroid hormones (T4 and T3).
Exposure to radiation is a further risk factor. Patients who have been treated with radiotherapy for other conditions have an increased risk of thyroid cancer, as do people affected by nuclear fallout.
Medullary cancer (the least common of the thyroid cancers) is inherited in approximately 20% of cases.
Papillary and follicular thyroid cancers also seem to run in families occasionally but the genetic basis for this remains unknown.
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Prevention of Thyroid Cancers
Patients with a family history of any form of thyroid cancer should always be alert to the possibility that they too might be affected and seek advice at the earliest sign of any suspicious symptoms.
For all other patients there are no practical means of preventing thyroid cancer.
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Common Symptoms
- a painless lump in the front of the neck which gradually increases in size
- a painless lump (lymph node) to the side of the neck
- difficulty in swallowing and/or difficulty in breathing - both due to pressure effects of an enlarged thyroid gland on the oesophagus (gullet) and trachea (windpipe)
- hoarseness of the voice
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Diagnostic Tests
Suspected thyroid cancers can be tested by taking a sample through a needle (a fine needle aspirate) which is then examined for cancer cells.
An ultrasound scan can distinguish between solid lumps and fluid-filled cysts but not between benign and cancerous solid lumps.
Radioactive isotope scans are used to detect cancers as their cells absorb less radioactive iodine than normal thyroid cells and show up as “cold spots”, however, cysts and benign nodules will also show up as “cold spots” so this is not the best test to make a diagnosis.
There is no valid screening method using blood tests.
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Treatment
Thyroid cancers must be treated using surgery, usually removing the thyroid gland altogether and so removing the cancer.
Differentiated Thyroid Cancer (Papillary and Follicular Types)
Surgery, removing the thyroid gland completely, in some cases followed by administration of a radioactive isotope of iodine, I-131, given 4-6 weeks after surgery whilst the patient is hypothyroid and repeated if necessary.
Radioactive iodine is not an alternative to surgery, but a very useful additional treatment.
Medullary Thyroid Cancer
Surgery is performed to remove the thyroid gland and all the lymph nodes and fatty tissues.
External beam radiotherapy is also used to treat any remaining or relapsing areas of cancer.
Anaplastic Thyroid Cancer
In the early stage: surgery.
Other stages: external-beam radiation, in some instances combined with chemotherapy treatments.
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Key Trends
An increasing incidence of thyroid cancer over the past 25 years, but no increase in thyroid cancer deaths.
Earlier diagnosis leading to improved results.
Maintaining a high therapeutic success rate in Differentiated Thyroid Cancers while improving the quality of life of patients by avoiding repeated periods of hypothyroidism.
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Current Developments
Until recently, radioactive iodine could only be used if the patient is hypothyroid, which is why it is not given until six weeks after surgery. However, the introduction of recombinant TSH allows patients to be treated without waiting for them to become hypothyroid.
The use of monoclonal antibodies and radio-labelled peptides in the treatment of medullary cancer which has spread to other areas of the body.
Important Research Areas
To reduce the burden of treatment by using less aggressive treatment for thyroid cancer – in papillary and follicular cancer to give radioactive iodine to fewer patients and not to patients in the very low risk groups (those with a tumour less than 1cm in diameter).
Further assessment of current developments listed above.
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Unresolved Questions
The genetic susceptibility to thyroid cancers, in particular the papillary and follicular types.
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