At high doses, radiation kills cancer cells or slows their growth. Radiation therapy is used to:
Radiation can be used to cure cancer, to prevent it from returning, or to stop or slow its growth.
Radiation may be used to shrink a tumor to treat pain and other problems caused by the tumor. Or, it can lessen problems that may be caused by a growing tumor, such as trouble breathing or loss of bowel and bladder control.
Radiation therapy does not kill cancer cells right away. It takes days or weeks of treatment before cancer cells start to die. Then, cancer cells keep dying for weeks or months after radiation therapy ends.
External beam radiation therapy comes from a machine that aims radiation at your cancer. The machine is large and may be noisy. It does not touch you, but can move around you, sending radiation to a part of your body from many directions.
External beam radiation therapy treats a specific part of your body. For example, if you have cancer in your lung, you will have radiation only to your chest, not to your whole body.
Internal radiation therapy is a treatment in which a source of radiation is put inside your body. The radiation source can be solid or liquid.
Internal radiation therapy with a solid source is called brachytherapy. In this type of treatment, radiation in the form of seeds, ribbons, or capsules is placed in your body in or near the cancer.
You receive liquid radiation through an IV line. Liquid radiation travels throughout your body, seeking out and killing cancer cells.
External beam radiation therapy is used to treat many types of cancer. For some people, radiation may be the only treatment you need. But, most often, you will have radiation therapy and other cancer treatments, such as surgery and chemotherapy.
Brachytherapy is used to treat cancers of the head and neck, breast, cervix, prostate, and eye.
Liquid forms of internal radiation are most often used to treat thyroid cancer.
Radiation may be given before, during, or after surgery. Doctors may use radiation:
Radiation may also be given before, during, or after other cancer treatments to shrink the cancer or to kill any cancer cells that might remain.
Radiation not only kills or slows the growth of cancer cells, it can also affect nearby healthy cells. Damage to healthy cells can cause side effects. External radiation and brachytherapy cause side effects only in the part of the body being treated. The most common side effect of radiation therapy is fatigue, which is feeling exhausted and worn out. Fatigue can happen all at once or little by little. People feel fatigue in different ways. You may feel more or less fatigue than someone else who is also getting radiation therapy.
See the side effects section to learn more about fatigue and other side effects caused by radiation therapy.
Healthy cells that are damaged during radiation treatment almost always recover after it is over. But sometimes people may have side effects that are severe or do not improve. Other side effects may show up months or years after radiation therapy is over. These are called late effects. Your Doctors try to protect healthy cells during treatment by:
Using as low a dose of radiation as possible
The radiation dose is balanced between being high enough to kill cancer cells, yet low enough to limit damage to healthy cells.
Spreading out treatment over time
You may get radiation therapy once a day, or in smaller doses twice a day for several weeks. Spreading out the radiation dose allows normal cells to recover while cancer cells die.
Aiming radiation at a precise part of your body
With external radiation therapy, for example, your doctor is able to aim high doses of radiation at your cancer while reducing the amount of radiation that reaches nearby healthy tissue. These treatments use a computer to deliver precise radiation doses to a tumor or to specific areas within the tumor. To learn more about specific methods of radiation therapy, see Radiation Therapy for Cancer