Breast Cancer Treatment - Radiation Therapy

Radiation Therapy

Radiation therapy is an adjuvant treatment for most women who have undergone lumpectomy and for some women who have mastectomy surgery. In these cases the purpose of radiation is to reduce the chance that the cancer will recur. Radiation therapy involves using high-energy X-rays or gamma rays that target a tumor or post surgery tumor site. This radiation is very effective in killing cancer cells that may remain after surgery or recur where the tumor was removed.

Radiation therapy can be delivered by either external beam radiotherapy or brachytherapy (internal radiotherapy). In the case of external beam radiotherapy, X-rays are delivered from outside the body by a machine called a Linear Accelerator or Linac. In contrast, brachytherapy involves the precise placement of radiation source(s) directly at the treatment site. Radiation therapy for breast cancer is usually performed after surgery and is an integral component of breast-conserving therapy.

Radiation therapy eliminates the microscopic cancer cells that may remain near the area where the tumor was surgically removed. The dose of radiation must be strong enough to ensure the elimination of cancer cells. However, radiation affects normal cells and cancer cells alike, causing some damage to the normal tissue around where the tumor was. Healthy tissue can repair itself, while cancer cells do not repair themselves as well as normal cells. For this reason, radiation treatments are given over an extended period, enabling the healthy tissue to heal. Treatments using external beam radiotherapy are typically given over a period of five to seven weeks, performed five days a week. Each treatment takes about 15 minutes. A newer approach, called 'accelerated partial breast irradiation' (APBI), uses brachytherapy to deliver the radiation in a much shorter period of time. APBI delivers radiation to only the immediate region surrounding the original tumor and can typically be completed over the course of one week.

Although radiation therapy can reduce the chance of breast cancer recurrence, it is much less effective in prolonging patient survival. According to a review of six studies by the United States' National Cancer Institute, none of them found a survival benefit for radiation therapy. Patients who are unable to have radiation therapy after lumpectomy should consult with a surgeon who understands this research and who believes that lumpectomy (or partial mastectomy) alone is a reasonable treatment option.