Radiation

Radiation therapy uses high-energy x-rays to kill cancer cells or to shrink the size of a tumor in the breast or surrounding tissue. It is used for several weeks following lumpectomy or partial mastectomy, and sometimes after full mastectomy. Radiation therapy can help reduce the chance of breast cancer recurrence in the breast and chest wall. Radiation is also important in advanced stages of cancer for relief of symptoms and to slow progression. Research shows that radiation therapy is helpful for women of all ages, including those over age 65.

Administration of Radiation Therapy

Radiation is generally administered in the following ways:

External Beam Radiation. This type of radiation is administered 4 - 6 weeks after surgery and delivered externally by an x-ray machine that targets radiation to the whole breast. It may be delivered to the chest wall in high-risk patients (large tumors, close surgical margins, or lymph node involvement). The treatment is generally given daily (except for weekends) for about 6 weeks. A follow-up boost of radiation therapy in patients with lumpectomies appears to reduce the risk for recurrence.

Brachytherapy. Less commonly, radiation is delivered in implants (called brachytherapy). Implants are most often used as a radiation boost after whole breast radiation. Studies suggest they improve survival in patients at high risk for local recurrence. Some evidence suggests that implants alone can reduce treatment time and may be as effective as external beam radiation in some patients with early stage breast cancer. A new technology for breast brachytherapy (MammoSite) was approved in 2002. The technique provides 5-year local tumor control rates similar to those of whole-breast radiation for selected patients, with much shorter treatment time and good cosmetic results.

Investigators are also testing other approaches to radiation treatment. One uses a combination of neutrons and protons (mixed-beam) or proton beams rather than the standard photon radiation therapy. Intensity-modulated radiation therapy is a promising technique that delivers different doses to multiple target areas using images of specific regions. Such an approach may improve the coverage of breast cancers while reducing the toxic effects to the heart and lungs.

Side Effects of Radiation Therapy

• Fatigue is very common and increases with subsequent treatments, but most women are able to continue with normal activities. Exercise may be helpful.
• Nausea and lack of appetite may develop and worsen as treatment progresses.
• Skin changes and burns can occur on the breast skin. Using a cream that contains a corticosteroid, such as mometasone furoate (MMF), may be helpful. After repeated sessions, the skin may become moist and "weepy." Exposing the treated skin to air as much as possible helps healing. (Washing the affected skin with soap and water does not seem to be harmful and in one study was associated with a lower risk for this side effect.)
• Uncommonly, the breast may change color, size, or become permanently firm.
• Rarely, the nearest arm may swell and develop impaired mobility or even paralysis.

Long-Term Complications

• Radiation to the left breast may increase the long-term risk for developing heart disease and heart attacks.
• There is a very small risk (less than 1%) of lung irritation and scarring.
• Some studies have reported a higher risk for future cancer in the opposite breast in younger women who have been given radiation to the chest wall.
• Radiation therapy can increase the risk of developing other cancers, such as soft tissue malignancies known as sarcomas.

Current advanced imaging techniques use precise radiation that reduces exposure. These newer techniques are likely to reduce the risks for heart disease and other serious complications.

Review Date: 12/21/2006
Reviewed By: Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.

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