Incorporating Genomics Into the Care of Patients With Advanced Breast Cancer.

Metastatic breast cancer is a very heterogeneous disease. Recent advances in genomic sequencing have revealed genetic diversity between patients and across distinct subclonal cell populations within the same patient that may evolve across metastatic tumor sites and during treatment. With the increasing availability of commercial and laboratory-developed tests that can detect genomic alterations from patient tumor and blood samples, translating this knowledge into improved clinical care remains a challenge. The goals of this review are to outline the clinical relevance of tumor genomic heterogeneity and clonal evolution, to help clinicians understand how to interpret genomic testing reports, and to provide an overview of recurrent genomic alterations that may be relevant for clinical trials with investigational drug treatments.