Radiation

Radiation

Radiation therapy uses x-rays to kill cancer cells or to shrink the size of a tumor in the breast or surrounding tissue. Radiation therapy after mastectomy can reduce local recurrences in many high-risk patients, particularly those with four or more positive lymph nodes or an advanced primary cancer. Whether it adds benefits for women post mastectomy with one to three positive nodes is uncertain. Radiation is also important in advanced stages for relief of symptoms and to slow progression.

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.