[Molecular characterization of breast cancer in clinical practice]

Breast cancer involves various types of tumors. The objective of this review was to provide a summary of the main methods currently available in clinical practice to characterize breast cancers at a molecular level and to discuss their prognostic and predictive values. Hormonal receptors expression and the HER2 status are prognostic markers and can also predict the response to targeted therapies. Their analysis through immunohistochemistry is systematical. Ki67 is an effective prognostic marker, but its reliability is debated because of its low reproducibility between laboratories and between pathologists. Commercial genomic signatures are all considered valid prognostic tools and may guide physicians to make therapeutic choices. These signatures are costly and should therefore be restricted to situations in which the use of chemotherapy remains equivocal.