Detection of the oestrogen receptor (ER). immunohistochemical versus cytosol measurements

Oestrogen receptor (ER) content gives a direct indication of the chances that a breast cancer patient will show a sustained response to endocrine therapy. Thus, an ER value should be recorded for every breast cancer patient. ER was traditionally measured by a ligand binding assay (LBA). LBA is not suitable for all routine hospitals in which breast cancer is treated. More appropriate is immunohistochemistry (IHC). This paper identifies advantages and disadvantages of both assays, suggests that both methods predict equally response to endocrine therapies and describes a simple, semi-quantitative IHC for which external quality assurance works successfully.