What is external beam radiation for breast cancer treatment?

Traditional external beam radiation delivers a specific dose of radiation to the breast. Most patients being treated for breast cancer have had their tumor removed. They've undergone surgery where the cancerous area has been removed, but the breast is still there.

So the radiation is basically used as a preventative treatment to sterilize the rest of the breast. Patients are given small amounts of radiation every day for a period of between four and seven weeks. The dose varies depending on breast size and the stage of the cancer.

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This is the most common type of radiation therapy for women with breast cancer. The radiation is focused from a machine outside the body on the area affected by the cancer.
The extent of radiation depends on whether a lumpectomy or mastectomy was done and whether or not lymph nodes are involved. If a lumpectomy was done, the entire breast gets radiation, and an extra boost of radiation is given to the area in the breast where the cancer was removed to prevent it from coming back in that area. Depending on the size and extent of the cancer, radiation may include the chest wall and underarm area as well. In some cases, the area treated may also include supraclavicular lymph nodes (nodes above the collarbone) and internal mammary lymph nodes (nodes beneath the breast bone in the center of the chest).

When given after surgery, external radiation therapy is usually not started until the tissues have been able to heal, often a month or longer. If chemotherapy is to be given as well, radiation therapy is usually delayed until chemotherapy is complete.

Before your treatments start, the radiation team will take careful measurements to determine the correct angles for aiming the radiation beams and the proper dose of radiation. They will make some ink marks or small tattoos on your skin that they will use later as a guide to focus the radiation on the right area. You may want to talk to your health care team to find out if these marks will be permanent.

Lotions, powders, deodorants, and antiperspirants can interfere with external beam radiation therapy, so your health care team may tell you not to use them until treatments are complete.

External radiation therapy is much like getting an x-ray, but the radiation is more intense. The procedure itself is painless. Each treatment lasts only a few minutes, although the setup time—getting you into place for treatment—usually takes longer.

The most common way breast radiation is given is 5 days a week (Monday thru Friday) for about 6 weeks.

Possible side effects of external radiation: The main short-term side effects of external beam radiation therapy are swelling and heaviness in the breast, sunburn-like skin changes in the treated area, and fatigue. Your health care team may advise you to avoid exposing the treated skin to the sun because it may make the skin changes worse. Changes to the breast tissue and skin usually go away in 6 to 12 months.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.