Thyroid cancer: symptoms, signs, causes and treatment options

Medically reviewed: 7, December 2023

Read Time:3 Minute

What is thyroid cancer?

Thyroid cancers are fairly rare types of cancer, accounting for 1 in 100 of all cancers, with approx. 1,100 new cases in the United States each year. They usually grow slowly.

The thyroid gland is situated at the base of the throat. It absorbs iodine from the diet and produces thyroid hormones, which keep the body functioning normally.

There are three main types of cancer of the thyroid:

  • Papillary: the most common type, more common in younger people, predominantly women.
  • Follicular: less common found particularly in older people.
  • Medullary: a rare type which is sometimes, but not always, hereditary.

The outlook for most types of thyroid cancer is generally very good and many people are completely cured of the disease, even if it has spread beyond the thyroid.

Symptoms of the thyroid cancer

Symptoms of thyroid cancer can vary, depending on the type and spread. The first sign is usually a single, firm painless lump in the neck, which gradually increases in size.

Further symptoms arise when the tumor presses on the:

  • trachea (windpipe) causing difficulty in breathing,
  • oesophagus (gullet) causing difficulty in swallowing, and
  • nerves to the larynx (voice box) causing hoarseness or loss of voice.

Lymph nodes may become enlarged due to spread of the cancer to these nodes (Papillary). Very rarely, secondary tumors in the bones or lungs may cause the first symptoms after the cancer (follicular) has spread beyond the thyroid.

Any lump found in the neck should be seen by a doctor as soon as possible.

However, there are a number of more common benign conditions (eg goitre), which also cause a swelling in the neck.

Causes of thyroid cancer

The cause of Thyroid cancer is unknown.


Evidence suggests that previous exposure of the neck area to radiation increases the risk. This may be due to radiotherapy given in childhood, or when environmental levels of radiation become high (eg due to nuclear fallout following the Chernobyl nuclear accident).

The cancer is more common in women than men.

Medullary thyroid cancer can be hereditary, caused by an abnormal gene, which increases the risk of developing thyroid cancer. There are screening tests available to detect the gene faults responsible.

Diagnosis of a cancer of the thyroid

A GP’s initial physical examination cannot tell if a lump is cancerous or not. A blood test may be done to check thyroid hormone levels.

The doctor will arrange a referral to hospital for further tests, these may include:

Fine needle aspiration – small amount of thyroid tissue is extracted, so it can be looked at under a microscope to reveal any abnormalities (biopsy). This will confirm a diagnosis.

Ultrasound scan – this uses sound waves to show solid lumps or cysts. It may also be used to help find the thyroid lump during a needle biopsy.

Radioisotope scan / gamma camera scan – this uses a very small amount of radioactive iodine. Thyroid cells pick up iodine much more quickly than any other cells in the body but thyroid cancer cells do not pick up iodine as quickly so they will show up as ‘cold’ spots. The gamma camera measures the amount of radioactive substances taken up by the thyroid gland. This scan cannot tell whether a tumor is benign or cancerous.

Treatment of thyroid cancer

Treatment depends on a number of factors including age, general health, the type and size of the tumour, and whether it has spread beyond the thyroid.

Possible treatments for thyroid cancer include:

  • Surgery is often the main treatment for thyroid cancer. In most cases the whole thyroid gland will need to be removed (total thyroidectomy). Sometimes it is adequate to remove one lobe (partial thyroidectomy). These procedures are carried out under general anesthetic. Depending on the type of cancer, the lymph nodes may also be removed if they contain cancer cells.
  • Radioactive iodine treatment may be necessary following surgery. This will be taken as tablet, or a liquid. It is low dose radiation so treatment is monitored in hospital for a few days.
  • Radiotherapy and chemotherapy may also be used to treat cancer that has spread to other parts of the body.


People who work with radioactive substances eg nuclear industry workers, scientists, medical staff or students, should always observe health and safety guidelines to minimize any risk.

People who have a close relative diagnosed with thyroid cancer may wish to consider genetic testing.

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