Accelerated Partial Breast Irradiation, or APBI, is an accelerated and targeted form of radiation treatment for breast cancer that focuses only on the area where the tumor is removed, along with a small amount of healthy tissue around it. Rather than treating the entire breast daily over the course of five to six weeks, which has been the standard of care for anyone having a lumpectomy for breast cancer, APBI treats just the area around the tumor. This is the area where recurrences are most likely to occur. Because it is treating a smaller amount of tissue, it can be done safely over a much shorter timeframe. APBI can be delivered using a single radiation dose during surgery, or after surgery, over the course of five days.