Erika Hamilton, MD, Sarah Cannon Research Institute, Nashville, TN, discusses the importance of tailoring medicine in the treatment of early breast cancer, and cites the results of the KATHERINE trial (NCT01772472), evaluating trastuzumab emtansine versus transtuzumab as adjuvant therapy in patients with HER2-positive breast cancer who have residual tumor in the breast or axillary lymph nodes following preoperative therapy, where biology was used to inform treatment decisions. This interview was recorded via an online conference call with The Video Journal of Oncology (VJOncology).