A six to eight week course of irradiation therapy will be recommended for women undergoing lumpectomy (radiation therapy may be safely avoided in selected women with small, non-invasive cancers). The purpose of radiation is to eliminate any remaining cancer cells in the breast following lumpectomy, and it is very effective in lowering the rate of cancer recurrence in the breast.

Most women undergoing mastectomy usually do not require post-operative irradiation but in some cases; may.

Radiation therapy uses a beam of high-energy rays (or particles) to destroy cancer cells left behind in the breast, chest wall, or lymph nodes after surgery. Radiation may also be needed after mastectomy in cases with either a larger breast tumor, or when cancer is found in the lymph nodes.

This type of treatment can be given in several ways.

  • External beam radiation delivers radiation from a machine outside the body. This is the typical radiation therapy given after lumpectomy and is given to the entire breast with an extra dose (“boost”) to the site of the tumor. It is usually given 5 days a week for a course of 6 to 7 weeks.
  • Brachytherapy, also called internal radiation or interstitial radiation, describes the placement of radioactive materials in or near where the tumor was removed. They may be placed in the lumpectomy site to “boost” the radiation dose in addition to external beam radiation therapy.

Recently there has been interest in limiting radiation therapy only to the site of the lumpectomy, referred to as partial breast irradiation. This is based on the observation that when breast cancer recurs in the breast, the most common place is in the site of the original tumor. Brachytherapy is one technique of partial breast irradiation. External beam radiation therapy also can be used to deliver partial breast irradiation.

The extent of radiation depends on whether or not a lumpectomy or mastectomy was done and whether or not lymph nodes are involved. If a lumpectomy was done, the entire breast receives radiation with an extra boost of radiation to the area in the breast where the cancer was removed to prevent it from coming back in that area.

If the surgery was mastectomy, radiation is given to the entire area of the skin and muscle where the mastectomy was done if the tumor was over 5 cm in size, or if the tumor is close to the edge of the removed mastectomy tissue.

In patients who have had lumpectomy or mastectomy, further radiation may be recommended if the cancer has spread to the lymph nodes. Radiation may be given to the area just above the collarbone and along the breastbone, depending on the number and location of involved lymph nodes.

Side effects most likely to occur from radiation include swelling and heaviness in the breast, sunburn-like skin changes in the treated area, and fatigue. Changes to the breast tissue and skin usually go away in 6 to 12 months. In some women, the breast becomes smaller and firmer after radiation therapy. There may also be some aching in the breast.