Precision medicine in breast cancer

Precision medicine is a strategy for disease treatment and prevention that considers individual variability in genes, environment, and lifestyle. Historically, breast cancer has been treated according to biomarkers such as estrogen receptor and HER2 status. Currently, multigene assays are widely used to predict the risk of relapse after surgery. Molecular targeted agents have been investigated extensively, and some of them are clinically available to date. This review focuses on precision medicine, especially, genome medicine, in breast cancer.