IN HUMAN BREAST CANCER

More than 210,000 Americans will be diagnosed with breast cancer each year and more than 41,000 will die from this disease. Over the last two decades many novel therapies have been introduced. However, due to the limited availability and accuracy of prognostic and predictive markers, many patients will have to be treated for the benefit of a few. The lack of precise predictive markers not only pertains to the use of chemotherapy, but also to hormonal or targeted therapy. Still more than half of the patients treated will not derive a benefit. Currently, the prognosis and treatment plan for early stage breast cancer is based on the number of involved lymph nodes, the size of the tumor, the histological grade and type, as well as lymphatic and vascular invasion which will determine the potential benefits from adjuvant chemo- and radiation therapy. Further therapeutic intervention, targeting estrogen receptor and HER2 signaling pathways, are based on the qualitative and quantitative assessment of the estrogen receptor (ER) and progesterone receptor (PR) status and HER2 expression by immunohistochemistry or the HER2 amplification by prognostic and predictive values of gene expression patterns and the better definition of therapeutic targets will lead to significant change in the assessment and treatment of breast cancer in the near future.