Genomic and Molecular Classification of Breast Cancer.

At present, the biology of breast cancer remains poorly understood. Currently, lymph node metastases, tumor grade, and size, and expression of hormone receptors provide the only true prognostic and predictive factors related to clinical outcome and response to treatment, respectively. Many other potential candidates have been suggested but, due to their limited predictive power, have not been widely accepted by the general oncological community. These histopathological features do not allow us any insight into breast cancer biology, however, and these prognostic classifications are far from perfect. At present, due to these limitations many clinicians consider prescribing adjuvant treatment to many women with early breast cancer to reduce the risk of relapse, only to benefit a few, thus exposing many patients to unnecessary toxicity. Since the publication of the complete sequence of the human genome however, a new era of research has begun [1]. More than 3 billions base pairs form the 30,000-40,000 genes that code all the required genetic information of a particular individual. The functions of the vast majority of these genes are still unknown. [ABSTRACT FROM AUTHOR]