Importance of Biomarker Conversions as “Road Signs” to Manage Women with Metastatic Breast Cancer: How To Use Them for Personalized Care of These Patients?

During a metastatic progression of breast cancer (BC), and upon application of various antineoplastic therapies, the initial status of biomarkers can be altered. Awareness of changes in hormone receptors (HR) and human epidermal growth factor receptor 2 (HER2) is very important, because they may have an impact on patient management. However, the procedures for monitoring these changes in women with metastatic BC still remain unclear. According to the guidelines for clinical practice from the American Society of Clinical Oncology (ASCO), the reevaluation of metastatic BC lesions, is of great importance, and it has been recommended that the biopsies of multiple metastatic lesions need to be performed. The aim of this chapter is to highlight the role of retesting receptor status in BC metastases and the impact that this approach may have on the selection of therapeutic strategies, in the individualized management plans for patients with metastatic BC. In addition, this chapter concisely presents some novel biomarkers linked with targeted therapies for metastatic BC.