What Is Radiation Therapy?

Help someone with cancer make sense of the confusing world of radiation therapy.
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Internal radiation therapy for the treatment of cancer

Grappling with the concepts. When it comes to helping someone with cancer make treatment decisions, radiation therapy is one of the most difficult areas to understand and cope with. Even your friend or relative's oncologist may not be fully familiar with the latest procedures available.

Radiation therapy procedures are highly technical, which makes some of the concepts downright intimidating. What's more, a host of technological innovations over the past five years (with more coming quickly from clinical trials now underway) means that she will have many more options to sort through.

Don't let intimidation keep you from being an active participant in her care, though. Ask her doctor as many questions as you need to until you understand how the recommended procedures work. For help discussing these options with the doctor, see 15 Questions to Ask About Radiation Therapy for Breast Cancer.

When is internal radiation recommended? Radiation therapies can be internal or external. Doctors usually recommend internal radiation, also called brachytherapy, when the goal is a high dose of radiation delivered internally to a small area, as in the treatment of breast or prostate cancer or cancers of the head and neck. The radiation is implanted or injected in the form of wires, "seeds," or capsules, then left in place for a period of time, either until it's removed or until it decays and becomes inactive.

Brachytherapy is usually done as an outpatient procedure, though the person you're caring for may also have a radioactive source implanted at the end of surgery. The root word brachy means "short distance," and brachytherapy can be thought of as concentrated radiation from a short distance. Intracavity brachytherapy indicates that the doctor places the radiation into an existing cavity, while interstitial brachytherapy is the term for placing the radiation directly in tissue. MammoSite brachytherapy is arelatively new procedure used to treat breast cancer in which radiation is delivered in the form of a balloon catheter. The balloon is surgically placed where the tumor was removed, and seeds of radiation are delivered through the catheter into the balloon.

Intraoperative radiation therapy, or IORT, refers to radiation that's delivered to the area where a tumor was removed immediately following surgery. Doing this allows the radiation source to be positioned exactly where it will do the most harm to cancerous tissue, while nearby organs and healthy tissue are protected with shields. New portable radiation units now make it possible for IORT to be completed in the operating room at the end of a surgical procedure. Brachytherapy is the most common form of IORT, but for some types of cancer, doctors use external electron beam radiation immediately after surgery.

External radiation therapy for the treatment of cancer

External radiationcovers all types of therapy in which radiation is beamed into the body from an outside source, most often an X-ray machine or linear accelerator. It's usually given in the form of a sequence of treatments, typically five days a week for six to eight weeks. (On weekends, your friend or relative gets a break so his body can recover.)

Radiation can be done before a tumor is surgically removed in order to shrink it, or after surgery to catch stray cancer cells, or it can be used as a stand-alone therapy.

Standard radiation therapy, which has been in use in various forms for more than two decades, is a form of external radiation that uses large cross-firing beams from an X-ray machine or linear accelerator to target the tumor and the edge of surrounding tissue, sometimes called the margin. Many hospitals now offer a variety of more advanced radiation techniques, such as 3-D conformal radiation therapy (known as 3D-CRT), in which MRIs and other computer imaging techniques are used to map the tumor three-dimensionally so that the beams of radiation can more closely match the outlines of the tumor and damage less of the surrounding tissue.

Technological advances. In recent years, new computer-assisted imaging techniques, new radiation machines, and other technological advances have vastly increased the number of options available under the umbrella of external radiation. For more specific information about choosing or advocating for the latest advances in radiation therapy, see Guide to Intensity-Modulated Radiation Therapy and the Latest Technology.

Systemic radiation therapy. If the person you're caring for has thyroid cancer or non-Hodgkin's lymphoma, the doctor may recommend systemic radiation therapy, which is overall radiation that travels throughout the body. She'll be given a dose of radioactive material such as strontium 89 or iodine 131, either orally or by injection. The radioactive material leaves her body through urine, sweat, and saliva, so special precautions are necessary for you or whoever is the caregiver if systemic radiation is the treatment of choice.

Melanie Haiken

Melanie Haiken discovered how important it is to provide accurate, targeted, usable health information to people facing difficult decisions when she was health editor of Parenting magazine. See full bio