Breast cancer classification divides breast cancer into several categories according to multiple different schemes, each based on different criteria and serving a different purpose. A typical description usually considers each of these aspects in turn: the histolopathological type, the grade of the tumor, the stage of the tumor, and the expression of proteins and genes. As knowledge of cancer cell biology develops these classifications are updated. The practical purpose of classification is to describe each individual instance of breast cancer in a way that helps select which treatment approach is anticipated to have the best chance for a good outcome, with increased efficacy and low toxicity...