Molecular genetic tests in the prediction of the prognosis of breast cancer
Breast cancer is a heterogeneous disease concerning its morphology and behaviour. Until a few years ago, the prognosis of a given breast cancer case was mainly defined based on several parameters included in the pathology report: pTNM, grade, type, lymphovascular invasion, hormone receptor status and HER-2 status. The risk categories defined in the most recent St. Gallen consensus documents were complemented by the addition of the Ki67 index provisionally as a good marker for prognosis and for the risk of progressive disease. Newer assays are being developed to help augment these standard pathologic markers. The application of emerging molecular techniques in oncology is giving way to a variety of new prognostic and predictive tests designed to help tailor patient-specific treatment algorithms. While a few of these have accumulated sufficient validation to merit their use in the routine work-up of certain cancers, most still need additional studies to validate their roles in patient management. This review gives an overview of the major molecular pathology tests that are currently available for routine diagnostics. We provide information about their development, technical issues, and current and emerging utility as prognostic and/or predictive studies. Additionally, we discuss tests that are currently under investigation requiring additional validation.