Clinical implications of breast cancer tumor genomic testing

One of the important applications of genetic testing is genetic testing of the tumor to identify non-inherited somatic mutations. The advent of high-throughput genomic and proteomic techniques has enabled characterization of genomic alterations and accelerated development of novel matching therapies for cancer. Consequently, mutational status has increasingly defined treatment selection for patients with solid tumors. The effectiveness of targeted therapy depends on matching with the right target; targets that are differentially expressed in tumor cells and provide growth and survival advantage. Currently, multiple targeted therapies have been approved by the Food and Drug Administration (FDA) for treatment of solid tumors including breast, lung, and melanoma, while many others are being evaluated in clinical trials. In addition to identifying actionable genomic alterations of interest, tumor genome sequencing also has the potential to detect germline mutations that has clinical implications for both the patient and their family. While targeted therapies have transformed our approach to cancer care in solid tumor patients within the past decade, lack of sustained responses and emergence of acquired resistance limit their clinical activity. In this article, we discuss tumor genome sequencing in breast cancers and their clinical implication.