Trastuzumab has revolutionized the treatment of HER2+ breast cancer; however, the benefit of a longer duration of this therapy is uncertain. The PERSEPHONE trial (ISRCTN52968807) looked at the efficacy of 6-month vs. 12-month adjuvant trastuzumab use in patients with HER2+ early breast cancer. In this interview, Robert Coleman, MBBS, MD, FRCP, FRCPE, of the University of Sheffield, Sheffield, UK, discusses the results of this study and their wider implications.This video was recorded at the American Society of Oncology (ASCO) 2018 Annual Meeting, held in Chicago, IL.