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 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.
With radioablation therapy, you may experience the following unpleasant effects:
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.
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.
With external radiation therapy, you may experience the following unpleasant effects:
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Last reviewed September 2016 by Mohei Abouzied, MD, FACP Last Updated: 9/17/2014