PERSPECTIVE Gene-Expression Profile: The Future in the Outcome Prediction and Treatment of Breast Cancer

The malfunctioning of specific genes drives probably the development and progression of neoplastic disease. Indeed, recent studies using microarray analysis provide evidence that breast cancer tumors can be classified according to their gene-expression profiling into subgroups with poor prognosis and good prognosis. These works represent a considerable advance in the clinical application of microarray technology. The fascinating of these studies is that the DNA-microarray data predict the outcome –overall survival and distant metastases- much better than such classic prognostic indicators as nodal status, grade, stage, and estrogen-receptor status. The finding that the genetic signature of a breast cancer is strongly associated with outcome independently of nodal status has important biologic implications and may change the current therapeutic strategy regarding clinical decision making about adjuvant chemotherapy in some individuals who at present either overtreated or undertreated. lthough the incidence of breast cancer in the western world still remains high, mortality has been reduced over the last decades. This improvement is partially attributable to an effectiv