Radiation Medicine Rounds is a trinary, hard cover, periodical designed to provide an up-to-date review of a dedicated radiation medicine topic of interest to clinicians and scientists who are involved in the care of patients receiving radiotherapy. It is intended to serve as both a reference and instructional tool for students, housestaff, fellows, practicing clinicians, medical physicists, cancer biologists, radiobiologists, and interdisciplinary colleagues throughout the oncology spectrum. This issue of Radiation Medicine Rounds discusses the more salient topics surrounding the role of radiation therapy in breast cancer. The specialty of radiation therapy has increased in complexity over the years, yet as technology improves, the goal of improving outcomes while decreasing toxicity remains critical. Breast Cancer provides the practitioner with a full current overview of the present best practices and recent research in management of this complex and challenging cancer.