External beam radiation therapy for thyroid cancer

External beam radiation treatment uses high-energy rays to destroy cancer cells or slow their growth. A focused beam of radiation is given from a machine outside the body. This type of radiation treatment is not used much for cancers that take up iodine (that is, most papillary and follicular thyroid cancers), which are better treated with radioactive iodine (RAI). It is more often used as part of the treatment for medullary thyroid cancer and anaplastic thyroid cancer.

Radiation is most often given 5 days a week for several weeks. The treatment itself is painless and is much like getting a regular x-ray. Each treatment lasts only a few minutes, although the setup time — getting you into place for treatment — usually takes longer.

Possible side effects

The main drawback of this treatment is that the radiation can destroy nearby healthy tissue along with the cancer cells. Some patients get skin changes like a sunburn, but this slowly fades away. Trouble swallowing, dry mouth, hoarseness, and fatigue are also possible side effects of radiation aimed at or near the thyroid.

To reduce the risk of side effects, doctors carefully figure out the exact dose needed and aim the beam as accurately as they can to hit the target.

To learn more about radiation therapy, see our document, Understanding Radiation Therapy: A Guide for Patients and Families.