Thyroid Cancer


  • No symptoms
  • Lump in thyroid
  • Enlarged thyroid
  • Hoarseness
  • Difficulty swallowing
  • Shortness of breath
  • High-pitched breathing


Thyroid cancer starts in the thyroid gland causing cells to experience abnormal growth. There are many different types of thyroid cancer. The different types are defined by which thyroid cell the cancer affects. The most common is differentiated thyroid cancer. There are two types: papillary carcinoma and follicular carcinoma. The other types of thyroid cancer, such as medullary thyroid carcinoma and anaplastic thyroid carcinoma, are rarer.

Papillary Carcinoma

This type of thyroid cancer accounts for around 90% of cases. Tumor growth is relatively slow. The cancer responds well to treatment, and the cancer is rarely fatal. It takes place in the lobes of the thyroid gland and can sometimes spread to the lymph nodes.

Follicular Carcinoma

This type of differentiated thyroid cancer is the rarer of the two. It affects the follicular cells of the thyroid, which are responsible for converting the iodine of the blood to thyroid hormone. This hormone helps the body control how it uses energy.


The cause of differentiated thyroid cancer is unknown. There are a certain number of risk factors linked to disease development. Thyroid cancer risk factors are anything that may influence the chances of a person getting thyroid cancer.

  • Gender - Women have a higher chance of developing thyroid cancer than men.
  • Age - Thyroid cancer is more common in the age groups of 40-50 years old in women and 60-70 years old in men.
  • Ionizing radiation - Exposure to high dose radiation in adolescence and childhood is a well-established risk factor for thyroid cancer. Exposure to radiation can happen during medical treatment, and on a larger scale, during nuclear power plant accidents.
  • Previous thyroid disease - Individuals who have had a benign (non-cancerous) thyroid tumor have an increased risk of developing thyroid cancer.
  • Family History - A family history of thyroid cancer increases the risk of developing the disease.


There are a number of therapies for differentiated thyroid cancer. Treatment is guided by the age of the patient and pre-existing medical conditions.


This is a popular treatment for thyroid cancer. Depending on whether the cancer has metastasized (spread from the primary site on the thyroid to other tissues), all or part of the thyroid may be removed. A risk in this surgery includes damage to the laryngeal nerve, which can result in the patient developing breathing problems.

Radioactive Iodine Treatment (RIT)

During RIT, large doses of radioactive iodine are given. As the thyroid absorbs iodine from the blood, the radioactive iodine kills cancer cells in the thyroid gland. This treatment can be used alone or as a secondary treatment after surgery. Complications include a buildup of fluid in the neck area, inflammation of the thyroid, and inflammation of the salivary glands.

Thyroid Hormone Treatment

If the thyroid gland is removed, a person will need to take thyroid hormone replacement drugs. These prevent hypothyroidism and reduce the risk of the thyroid cancer cells returning. Levothyroxine (Synthroid*) is a commonly used thyroid hormone replacement drug.

External Beam Radiation Therapy

Radiation is delivered to the cancerous thyroid cells, destroying and slowing cancer growth. Typically, this type of treatment is used for the less common medullary and anaplastic thyroid cancers. Complications can result from the radiation by destroying healthy cells in addition to the targeted cancerous cells.

Additional Resources

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  • American Cancer Association. (2013). What is Cancer?
  • American Cancer Society. (2013). External beam radiation therapy for thyroid cancer.
  • American Cancer Society. (2013). Radioactive iodine treatment for thyroid cancer.
  • American Cancer Society. (2013). What are the risk factors for thyroid cancer?
  • American Cancer Society. (2013). What is thyroid cancer.
  • Kenneth, J., Yawn, R., Wilhoit , C. S., Sora, N. D., Meyers, L., Fernandes, J., & Day, T. (2012). Well Differentiated Thyroid Carcinoma: Current Treatment. Current Treatment Opinions in Oncology.
  • Fernandes, J. K., Day, T. A., Richardson, M. S., & Sharma, A. K. (2005). Overview of the Management of Differentiated Thyroid Cancer. Current Treatment Options in Oncology.
  • Nix, P., Nicolaides, A., & Coatesworth, A. P. (2005). Thyroid cancer review 1: Presentation and investigation of thyroid cancer. International Journal of Clinical Practice.
  • Meman, A., Berrington de Gonzalez, A., Luqmani, Y., & Suresh, A. (2004). Family History of Benign Thyroid Disease and Cancer and Risk of Thyroid Cancer. European Journal of Cancer.

Page updated: January 6, 2023