F.A Tavassoli

At the turn of the century, technological advances made it possible to determine a cancer’s molecular signature. A umor’s molecular signature is increasingly combined with its clinical and morphologic aspects in an attempt to provide an improved taxonomy of cancers, to refine prognostication as well as to utilize a more precise and personalized therapy. Several molecular subtypes of breast cancer have been defined and attempts have been made to use immunohistochemical surrogates to identify these tumors on the basis of their immunoreactivity. The evolution of the molecular intrinsic subtypes of breast cancer will be presented and correlated with their morphologic counterparts along with their biomarker expression. As more breast cancers are studied at the molecular level, it is becoming evident that there are more subtypes than initially anticipated. Furthermore, none of these subtypes reflect a pure or uniform tumor population. As we focus on identifying targets for therapy, it is important to keep in mind that there is not sufficient evidence to support that all tumors with a given target will uniformly respond to the therapy directed at that target- an example of this is Her2 enriched/positive cancers that do not uniformly respond to Herceptin therapy. At present, we use a combination of tumor’s morphology, biomarker status, stage and its molecular features to optimize management of breast cancer patients always incorporating an individual patient’s health status and family history of breast cancer in the final decision.