Breast cancer prognostic and predictive factors

The purpose for developing prognostic and predictive factors is to assist oncologists to optimize treatment decisions for every patient. Prognostic factors evaluate risk, and so are informative of the inherent biological aggressiveness of a patient's breast cancer. Tumor stage, nodal status, grade, estrogen receptor status, and a patient's age have known prognostic value and are combined in the Adjuvant! online site as a valuable tool for clinical care. Molecular diagnostic tests of gene expression have been developed to supplement known prognostic factors. While these tests are not yet standard of care, they could become useful for particular subsets of breast cancer patients for whom the additional information from the molecular test would be likely to change the recommendation of whether to offer systemic therapy. Predictive factors evaluate the likely benefit to be gained from a specific treatment. Examples include evaluation of ER for hormonal therapy and HER-2 for trastuzumab therapy. These are the most widely used tests in breast cancer because the results directly support an oncologist's recommendations about these therapies. There are currently no predictive tests for other systemic treatments, but recent progress in this area is discussed.