Frequency and reliability of oestrogen receptor, progesterone receptor and HER2 in breast carcinoma determined by immunohistochemistry in Australasia: results of the RCPA Quality Assurance Program.

Background And Aims: Immunohistochemistry (IHC) has replaced radioligand binding assay for the determination of oestrogen receptor (ER) status in breast carcinoma. IHC is also used for assessment of progesterone receptor (PR) and HER2. The Royal College of Pathologists of Australasia (RCPA) Quality Assurance Program (QAP) introduced a breast markers module in 2003 to evaluate the performance of laboratories with IHC for ER, PR and HER2.