How safe is external-beam radiation treatment for thyroid cancer?

Not common treatment: External beam radiation is seldom used for thyroid cancer. Usual treatment is surgery, radioactive iodine, and supressive doses of synthroid (thyroxine). However, ext beam rt can be used when there is extensive disease, unresectable disease, or for additional targeting of local tumor; maybe bone metastases. There are side effects, but usually there is advanced disease, and the treatment is needed.

Unusual: In most cases, external beam should be considered only if i-131 and surgery have failed. Targeting a single brain or bone lesion with external beam can be done, usually with limited side effects, but the goal is usually not for cure in those cases. Depending on the specifics, some thought should be given to a tyrosine kinase inhibitor as a third-line treatment.

Very much so: Indications for external beam radiation for thyroid cancer are if there was a positive margin after resection, lymph nodes involved at time of resection, or progression in spite of other treatments. Usually it will involve the supraclav node region and possibly the thyroid bed. This can cause temporary irritation of the throat or nerves controlling your arm. Skin irritation can occur as well.