Breast cancer

Abstract

Breast cancer treatment has evolved over the past 50 years, often as a direct consequence of molecular testing advances. In fact, molecular testing of predictive markers in breast cancer, including hormone receptors and HER2, is the model for personalized cancer treatment. Clinical practice guidelines specify that every primary invasive breast cancer and putative recurrence be tested for ER, PR, and HER2 expression to identify those cancers likely to respond to corresponding targeted treatments. The newest tests for breast cancer management are the tissue-based prognostic and/or predictive molecular assays, which identify patients with biologically indolent breast cancer who will not benefit from cytotoxic chemotherapy and those with intrinsically aggressive disease who may benefit. This chapter reviews clinically standard predictive marker and Oncotype DX® testing, as well as several emerging molecular testing systems.