Radiation Therapy

What Is It?

Radiation therapy is a form of cancer treatment that uses ionizing radiation (an intense form of energy) to damage or destroy cancer cells. Ionizing radiation attacks cancer cells by harming their genetic material, which kills them or interferes with their ability to grow and multiply. During radiation therapy, normal cells located near the cancer cells can be damaged as well, but these usually are able to recover and survive.

Radiation therapy can be given externally in the form of X-ray beams, gamma rays or beams of subatomic particles. Treatment with external radiation is usually painless and takes five to 15 minutes per session. The number of treatments varies for each person. In some cases, therapy can take several weeks of closely scheduled sessions.

Radiation also can be delivered internally. Radioactive substances either are placed inside a body cavity or implanted inside the tumor itself.

Some innovations that can increase the effectiveness of radiation therapy include:

• Conformal beam techniques — Radiation is delivered from many beams at the same time. This allows the radiation to be concentrated on the tumor with less damage to nearby normal tissues.
• Intraoperative radiation therapy — Radiation is delivered to a tumor during surgery.
• Radiosensitizers — These drugs increase radiation's damaging effect on cancer cells.
• Radioprotectors — These drugs protect normal cells from radiation damage, while nearby cancer cells are destroyed.
• Radioimmunotherapy — Radioactive substances are attached to antibodies, which are defensive chemicals made by the body's immune system. These antibodies specifically target cancer cells and deliver damaging radioactivity only to them. Because the antibodies do not attack noncancerous, healthy cells, this reduces the potential for radiation damage outside the tumor.

What It's Used For

Radiation therapy is used to treat many types of cancer, including cancer of the lung, breast, prostate, testicles, lymphoid tissues and brain.

When a tumor is going to be removed surgically, radiation also can be used first to help shrink the tumor and to reduce the amount of normal tissue that needs to be removed near the tumor. When cancer has spread, radiation therapy can be combined with chemotherapy or surgery to give a better chance for a cure, or to help reduce symptoms that are caused by the cancer spreading to other areas.

Preparation

Because radiation therapy can affect your teeth, you should visit your dentist to have any major dental work done before beginning radiation treatments to the head and neck. Also, because radiation of certain body areas can increase your risk of infertility or sterility, you should discuss family-planning issues with your doctor, including the option of sperm banking. You also should check with your doctor before therapy to see if any of your current medications could cause problems during radiation therapy. As with chemotherapy, if you are a woman and there is a possibility that you might be pregnant, you should tell your doctor before starting treatment.