Radiation oncology uses different forms of high-energy beams to damage cancer cells. In breast cancer patients, it is most often recommended for women who have had a lumpectomy or part of a breast removed, or women who have undergone mastectomy but had several lymph nodes involved with their cancer. Radiation therapy is used to help prevent the recurrence of cancer by destroying any microscopic breast cancer cells remaining after surgery, and to radiate the breast tissue to prevent it from re-creating breast cancer cells.
Johns Hopkins Kimmel Cancer Center’s radiation oncology team for breast cancer, led by Richard Zellars, MD, has adopted the Canadian method of radiation therapy for breast cancer, in which treatments are given every weekday for just four weeks, compared to the U.S. standard of 6.5 weeks. Each treatment lasts just 2-3 minutes and is painless, though some patients experience mild side effects including a sunburn-type reaction of the skin, fatigue, armpit discomfort, or transient chest pains.
Patients most often receive external beam radiation, in which the patient lies on a table and part of a machine is directed at either a specific area of the breast, or the whole breast.
Dr. Zellars and colleagues are actively pursuing a number of clinical trials designed to improve radiation therapy and its outcomes. One is studying the safety of combined radiation and chemotherapy in which women receive three weeks’ of radiation therapy overlapping with their first two cycles of chemotherapy. This takes the average time of treatment of chemotherapy followed by radiation from an average of six months down to less than two months.
In the trial, women receive partial breast irradiation that lasts daily for three weeks compared to seven. Because a smaller area of tissue receives the radiation, a larger dose can be given each day --- allowing patients to receive the same effective dose of radiation in a shorter period of time. Chemotherapy is given once every two weeks and is started at the same time that radiation begins. The bi-monthly chemotherapy lasts an extra 4 weeks after the radiation ends. In addition to shortening the duration of daily radiation treatments in the combined approach, the investigators believe that the radiation may make the breast cancer cells more sensitive (and more likely to be killed) by the chemotherapy. Results of a study of 25 women published in the Journal of Clinical Oncology in 2009 showed that the patients’ side effects were lessened with the combined therapy. A study in a larger number of women is now underway.
Another trial is studying proteins in the blood of breast cancer patients. Blood samples taken from women undergoing radiation after lumpectomy are being studied to see if certain proteins may predict which patients may experience side effects from radiation.