Thyroid cancer is a type of cancer involving unregulated cell growth in the thyroid gland, which is located at the base of the neck. It is a rare type of cancer, accounting for approximately 1% of all people diagnosed with cancer.
Certain populations are at an increased risk of thyroid cancer and should, therefore, be advised to check for symptoms of thyroid cancer. Risk factors include:
- Asian ethnicity
- Aged between 25 and 65
- Family history of thyroid disease
- Previous radiation treatment to head or neck
The most common symptom of thyroid cancer is a lump or swelling in the throat, which is often painless. Any patient with a lump in the throat should be investigated for possible thyroid cancer, although only about 5% of lumps examined are found to be cancerous.
Symptoms of thyroid cancer may include:
- Lump or swelling in the throat
- Dyspnea and difficulty breathing
- Dysphagia and difficulty swallowing
- Persistent cough and hoarse voice
- Enlarged lymph nodes in neck
The symptoms of thyroid cancer are not specific to the disease and specific tests are therefore required to confirm the diagnosis.
After physical examination and a thorough medical and family history have been taken, a blood sample is usually needed. Additionally, imaging techniques are usually used to examine the thyroid gland such as ultrasound, computed tomography (CT) scan or magnetic resonance imaging (MRI). A laryngoscope can also be useful in the internal examination of the voice box.
A biopsy can be taken from the thyroid gland for microscopic examination in a laboratory for final confirmation of diagnosis.
There are four primary types of thyroid cancer including:
- Papillary carcinoma that usually affects young women under the age of 40 and is the most common type.
- Follicular carcinoma that often affects elderly populations.
- Medullary thyroid carcinoma that has hereditary characteristics and may run in families.
- Anaplastic thyroid carcinoma is the rarest and most aggressive type, usually affecting elderly people over 60.
Papillary and follicular carcinoma are often treated in a similar way, whereas medullary and anaplastic thyroid carcinoma warrant specific management plans according to the individual characteristics.
In most cases of thyroid cancer, surgical removal of the entire thyroid gland is usually the first step in the treatment plan. If the lymph nodes in the neck are also suspected to be affected by cancerous cells, these are also removed surgically.
Radiation therapy plays an important role in the treatment of thyroid cancer and may be used as the sole treatment or as adjuvant therapy following surgery. The radiation can be administered by way of an external X-ray beam aimed at the thyroid gland, or by taking radioactive iodine orally.
Chemotherapy may also be used, but is generally reserved as a second-line option after surgery and radiotherapy have not been successful. This is because it is a more general treatment that carries severe side effects for the entire body, whereas surgery and radiotherapy can easily be localized to the thyroid gland.
As the treatment of thyroid cancer renders the function of the thyroid gland insufficient, the normal actions of the thyroid gland are interrupted post-therapy. This predominantly affects the hormones that are produced by the thyroid gland – triiodothyronine (T3), thyroxine (T4) and calcitonin – which need to be administered pharmacologically on a lifelong basis.