External beam radiation therapy uses high-energy rays (or particles) to destroy cancer cells or slow their rate of growth. A carefully focused beam of radiation is delivered from a machine outside the body. Generally, this type of radiation treatment is not used for cancers that take up iodine (that is, most differentiated thyroid cancers), which can be more effectively treated with radioiodine therapy. It is more often used as part of the treatment for medullary thyroid cancer and anaplastic thyroid cancer.
When a cancer that does not take up iodine has spread beyond the thyroid capsule, external radiation treatment may help treat the cancer or reduce the chance of the disease coming back in the neck after surgery. If a cancer does not respond to radioiodine therapy, external radiation therapy may be used to treat local neck recurrence or distant metastases that are causing pain or other symptoms.
External beam radiation therapy usually involves treatments 5 days a week for about 6 weeks. The treatment itself is painless and 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.
Advantages of External Beam Radiation Therapy
- Radiation is an outpatient procedure that does not carry the standard risks or complications that accompany major surgeries (e.g., surgical bleeding, postoperative pain, the risk of stroke, heart attack or blood clot).
- The procedure itself causes no pain.
- If you are being treated for skin cancer, the aesthetic outcome of external beam radiation compared to mohs surgery.
- If you are being treated for prostate cancer, the risk of incontinence is minimal with radiation therapy.