Use and assessment of diagnostic and predictive markers in breast pathology

SummaryThe last 15 years or so have seen many changes in the practice of breast pathology relating to changes in methods of detection of breast disease and the increased use of markers for selecting specific forms of therapy. There have also been developments in immunohistochemistry and a much wider range of antibodies are suitable for use with formalin-fixed paraffin-embedded tissue. Immunohistochemistry can now be used to aid diagnosis in several areas such as benign vs malignant lesions, non-invasive vs invasive, and lobular neoplasia vs ductal carcinoma in situ. This review discusses the background to the different myoepithelial and luminal epithelial markers, with a discussion of their advantages and disadvantages diagnostically. The need to combine interpretation with histological findings is emphasized, along with the need for use of more than one marker. Methods of assessment of oestrogen receptors, progesterone receptors and HER-2 are described, with the problems that can occur. Regular audits are recommended to ensure reproducibility over time and uniformity.