For people with early breast cancer, delivering radiation therapy in fewer, larger doses does not increase the risk of long-term side effects from treatment, a new study demonstrates. The study, "Ten-Year Results of FAST: A Randomized Controlled Trial of 5-Fraction Whole-Breast Radiotherapy for Early Breast Cancer," was published in the Journal of Clinical Oncology. Radiation therapy, or radiotherapy, involves using X-rays — high doses of radiation — to kill cancer cells. In breast cancer, it is most commonly used following surgery, since radiotherapy can kill tumor cells that remain after such procedures. The therapy limits the possibility that the tumor will grow back. However, radiotherapy can also cause substantial injury to healthy tissue, resulting in side effects. The clinical trial FAST (ISRCTN62488883), which was initiated in 2004, tested whether changing the schedule in which radiotherapy is administered could reduce its side effects. The new follow-up study reports the results from this trial up to 10 years after the radiation therapy was given (median follow-up time 9.9 years). "