This document discusses targeted therapy for breast cancer. It begins by providing background on declining mortality rates for breast cancer over time. It then discusses how cancers develop multiple alterations that allow uncontrolled growth and outlines six essential alterations in cell physiology that contribute to malignancy. The document discusses molecular alterations that occur in breast cancer progression. It defines targeted therapy as drugs that target uniquely disrupted pathways in cancer cells. The document outlines several targeted therapies for breast cancer including hormonal therapies like tamoxifen, aromatase inhibitors, and fulvestrant. It discusses clinical trials demonstrating the benefits of these therapies. It also discusses therapies that target the HER2 receptor like trastuzumab and lapatinib. In summary, the document provides an overview of targeted