Radiation Therapy for Thyroid Cancer

Radiation therapy is the use of penetrating beams of high-energy waves or streams of ion particles to treat disease. Radiation therapy destroys the ability of cancer cells to grow and divide. It is used usually after surgical resection to get rid of remaining thyroid gland tissue or tumor spread elsewhere.

Two kinds of radiation therapy are available for treating thyroid cancer. One is delivered internally and the other is delivered externally.

Radioablation Therapy and Radioactive Iodine Therapy

Radioablation therapy or radioactive iodine therapy is used after thyroidectomy (surgical removal of the thyroid) to destroy any remaining thyroid cancer cells, cancerous lymph nodes, or spread of cancer to other areas of the body. Radioactive iodine therapy takes advantage of the fact that papillary or follicular cancers often take up iodine readily. A dose of radioactive iodine is given, thyroid cells take up the iodine, and the radioactivity kills them.

This type of therapy is only appropriate for patients with follicular or papillary thyroid cancer; medullary and anaplastic thyroid cancers don’t respond well to radioablation therapy.


Radiation therapy is not useful in thyroid cancers which normally do not concentrate iodide such as in anaplastic or medullary cancers. Pregnant patients should not receive radiation treatment.

This is a very effective way of killing any stray thyroid cancer cells remaining after thyroidectomy, cancerous lymph nodes, or thyroid cancer that has spread elsewhere in the body. Moreover, it is very effective in treating bone pain secondary to bony metastasis.

Side Effects and Possible Complications

With radioablation therapy, you may experience the following unpleasant effects:

  • If there are cancer cells elsewhere in your body, these areas may become briefly swollen and painful as the iodine collects in them.
  • Nausea and vomiting during the first day or so
  • Swelling or pain in your neck
  • Dry mouth
  • Brief loss of your sense of smell or taste

In addition, men who receive large doses of radioactivity may become infertile. Women don’t usually become infertile, but are often advised to avoid pregnancy for at least one year after radioablation therapy. There is a slight increased risk of developing a second cancer.

Post-treatment Care

  • Depending on the dose of radioactivity that you receive, you may have to be isolated in the hospital for several days to avoid exposing others to radiation.
  • Suck on hard candy or chew sugar-free gum to relieve dry mouth.
  • Drink a lot of water in the days and weeks following radioablation therapy to more quickly wash the radioactivity out of your bladder.

External Radiation Therapy

External radiation therapy is given to patients who have either inoperable or recurrent thyroid cancer that does not readily take up iodine, or metastasis elsewhere in the body that is not appropriate for treatment with radioactive iodine. It may also be given for palliation—to ease troublesome symptoms, such as difficulty swallowing, blocked airway, metastatic bone pain, and other symptoms.

In external radiation therapy, rays are directed at the tumor from outside the body. External beam radiation may help relieve difficult symptoms.


External radiation therapy can provide symptom relief and may be the only way to slow progression of inoperable tumors, such as anaplastic thyroid cancers.

Side Effects and Possible Complications

With external radiation therapy, you may experience the following unpleasant effects:

  • Dry, red, irritated skin
  • Fatigue
  • Difficulty swallowing
  • Hoarse voice


Baudin E, Schlumberger M. New therapeutic approaches for metastatic thyroid carcinoma. Lancet Oncol. 2007;8:148-156.
Cooper DS, Doherty GM, et al. The American Thyroid Association Guidelines Taskforce: management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid. 2006;16:1-33.
Cornett WR, Sharma AK, et al. Anaplastic thyroid carcinoma: an overview. Curr Oncol Rep. 2007;9:152-158.
Lee N, Tuttle M. The role of external beam radiotherapy in the treatment of papillary thyroid cancer. Endocr Ralat Cancer. 2006;13:971-977.
What is thyroid cancer. American Cancer Society website. Available at
...(Click grey area to select URL)
Accessed December 10, 2002.
What you need to know about cancer of the thyroid. National Cancer Institute website. Available at
...(Click grey area to select URL)
Accessed December 10, 2002.
Last reviewed September 2016 by Mohei Abouzied, MD, FACP
Last Updated: 9/17/2014


EBSCO Information Services is fully accredited by URAC. URAC is an independent, nonprofit health care accrediting organization dedicated to promoting health care quality through accreditation, certification and commendation.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

To send comments or feedback to our Editorial Team regarding the content please email us at healthlibrarysupport@ebsco.com. Our Health Library Support team will respond to your email request within 2 business days.