Boston Cell Standards will present the results of a Canadian study that tested the first system of reference materials for standardisation of oestrogen receptor (ER) testing for breast cancer at the virtual San Antonio Breast Cancer Symposium.
As many previously published studies have demonstrated, high variability exists in the performance of ER testing when comparing different laboratories. For the first time, however, this new study also included immunohistochemistry (IHC) calibrators that defined a clear unit of measure – molecules of ER per cell.
Using these first units of measure, traceable to a National Institute of Standards and Technology (NIST) standard, analytical sensitivities of individual ER assays were quantified. These new testing tools clearly demonstrated a defined analytical sensitivity threshold at which ER testing becomes suboptimal, missing most weakly positive cases.
Although all the clinical ramifications of this threshold cannot be known without further studies, the new measurement tool provides critical information that can be used to track variability among laboratories, reagent lots, and even day-to-day runs, potentially lowering error rates in IHC laboratories.
Termed IHCalibrators, these new tools were developed by Boston Cell Standards in collaboration with NIST, and are the first of their kind in the IHC industry.
The study was performed by the Canadian Immunohistochemistry Quality Control (CIQC) programme, which offered Canadian ER testing laboratories the opportunity to test 80 different breast cancer patient samples, as a check to verify that they obtain the correct answers. Also included were the new reference materials, capable of measuring a laboratory’s analytical sensitivity of their ER test. The performance of the new tool was correlated with the laboratory’s ability to accurately distinguish positive and negative patient samples.