In radiation therapy, strong, high-energy rays kill cancer cells or slow their growth. In external radiation therapy, the radiation is aimed at the cancer from a source outside the body.
External radiation is a local therapy, affecting the cancer cells only in treated areas. This type of radiation, may be given alone, with chemotherapy or with hormone therapy. It is sometimes used before or after surgery to shrink tumors or kill residual cancer cells. It may also be used to treat cancers that cannot be removed surgically. A typical treatment course may include external radiation therapy five days a week for about six weeks. Although the actual treatment time is usually just a few minutes, it takes more time to get you into place and set up the procedure.
External beam radiation therapy is used to treat thyroid cancers that do not take up iodine, such as anaplastic or medullary cancer. It is also helpful when radioactive iodine (RAI) was tried, but the cancer cells did not absorb the iodine well. It can additionally be used to treat areas where the cancer has spread, such as the bones. It is sometimes used in combination with chemotherapy to treat anaplastic cancer.
Radiation therapy affects normal cells as well as cancer cells. Common side effects of external radiation for thyroid cancer can include fatigue, trouble swallowing, hoarseness, loss of appetite, low blood counts, and nausea. The person's skin may also feel and look sunburned in the treated area, but this is usually temporary.