What is thyroid cancer?
There are several different types of thyroid cancer, the most common is papillary thyroid cancer, which usually grows in one lobe of the thyroid gland (about 70-80% of all cases). Follicular thyroid cancer accounts for about 25% of thyroid cancers.
Less common thyroid cancers include medullary thyroid cancer, anaplastic thyroid cancer and thyroid sarcoma or lymphoma.
Thyroid cancer symptoms
The symptoms can include:
- a lump in the neck or throat that may get bigger over time
- difficulty breathing or swallowing
- swollen lymph glands in the neck
- diarrhoea or constipation
- a hoarse voice.
You should talk to your GP if you have any of these symptoms, as often thyroid cancer develops slowly, without obvious signs or symptoms.
Causes of thyroid cancer
It is unknown what causes thyroid cancer, however there are known risk factors, including:
- a family history of the faulty gene called RET gene
- having a thyroid condition such as an enlarged thyroid (goitre) or thyroid nodules
- exposure to some forms of radiation, such as childhood radiotherapy treatment.
Screening for thyroid cancer
There is currently no screening for thyroid cancer.
Diagnosis for thyroid cancer
If your doctor suspects you may have thyroid cancer, you will have one or more of the following tests:
A blood test will check the levels of hormones (including T3 and T4) and the thyroid-stimulating hormone (TSH). A blood test can also help to identify non-cancerous thyroid conditions, such as hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid).
A painless scan that takes about 20 minutes, an ultrasound produces pictures of internal organs. It can assist in determining if any lump in your neck is solid or fluid filled. It will also show whether any lymph nodes have been affected.
A doctor removes some of the thyroid tissue for examination under a microscope. The most common type of biopsy is called a fine needed aspiration, alternatively a doctor may do a hemi-thyroidectomy to remove tissue sample.
This test is usually done if blood tests indicate an overactive thyroid (hyperthyroidism). A small amount of radioactive liquid (such as iodine) is injected into a vein in your arm prior to a gamma camera scan being done. The amount of radioactive liquid taken up by the thyroid gland is then measured.
If cancer is detected in your thyroid, you may have other scans to see if the cancer has spread to other parts of your body, such as a CT scan or MRI scan.
Treatment for thyroid cancer
Most people with thyroid cancer receive a combination of treatments from surgery, thyroid hormone replacement therapy, radioactive iodine treatment, radiotherapy or chemotherapy. This will depend on the type and stage of thyroid cancer you have.
The most common form of treatment is surgery, whereby a section or the whole thyroid gland is removed (partial or total thyroidectomy). As a preventative measure, the surgeon may also remove nearby lymph nodes (called a neck dissection).
Thyroid hormone replacement therapy is given as a daily tablet to replace the thyroid hormones (thyroxine or T4) that your body can no longer produce after surgery. If you have had thyroid surgery you will need Thyroxine replacement for the rest of your life as it is very important to keep your body functioning at a normal healthy rate.
Radioactive iodine treatment
A form of internal radiotherapy, Radioactive iodine treatment is typically taken in a gel tablet form. It destroys any cancer cells left behind after surgery. Talk to your doctor about the safety measures required for this type of treatment.
External radiotherapy (the use of high energy x-rays) may be given after surgery, particularly if the cancer has spread to lymph nodes in the neck, or for thyroid cancers that are less responsive to radioactive iodine treatment (such as medullary or anaplastic thyroid cancers).
Chemotherapy is sometimes used to treat thyroid cancer that is not responding to radioactive iodine treatment. It is usually given as a drug that is injected into a vein (intravenously).
Although it is most often used by people with advanced cancer, palliative treatment can be used at any stage of cancer treatment. It is intended to improve a person's quality of life by alleviating the symptoms of cancer, without trying to cure the disease. It can include pain relief, and the management of other physical and emotional symptoms.
Depending on your treatment, your treatment team may consist of a number of different specialist staff, such as:
- an endocrinologist, who specialises in diagnosing and treating disorders of the endocrine system
- an endocrine surgeon, an ENT surgeon, who treats the ears, nose and throat, or a head and neck surgeon
- a nuclear medicine specialist
- a cancer nurse
- other allied health professionals, such as dieticians and physiotherapists.
Prognosis for thyroid cancer
It is not possible for a doctor to predict the exact course of a disease, as it will depend on each person's individual circumstances. However, your doctor may give you a prognosis, the likely outcome of the disease, based on the type of thyroid cancer you have, the test results, the rate of tumour growth, as well as your age, fitness and medical history.
The most common types of thyroid cancer have very good long-term prognosis, especially if the cancer is found early.
Of all cancers, thyroid cancer has the highest five-year survival rate at 96%. The prognosis for women is slightly higher at 97%.
Preventing thyroid cancer
As there is no known cause for most thyroid cancers, it is not possible to prevent most cases of this disease.
However, if Familial medullary thyroid cancer is detected in a family, the rest of the family can be tested for the mutated gene. If a family member has the mutated gene, they can elect to have preventative treatment, such as surgery to remove the thyroid.