Proficiency testing (PT), which acts as an external quality control mechanism, is required in CAP-accredited laboratories that perform estrogen receptor (ER) and progesterone receptor (PR) by IHC and for all HER2 testing methods.
Two mandatory testing events are required per year for HER2, and one mandatory event is necessary for ER/PR. An unsatisfactory performance (less than 90% correct) on an event results in a report being issued to the accrediting agency. Laboratories with unsatisfactory PT performance may be required to submit corrective action reports or suspend testing until satisfactory performance is achieved.
