Criteria for the validation of HER2 IHC and ISH staining include:
- The laboratory must validate assay procedures before offering the test clinically.
- Concordance testing should be performed with a validated FISH assay and should be confirmed annually.
- The new test should show 95% concordance with a validated reference assay.
- It should be confirmed that only 5% or less of samples classified as either positive or negative disagree with that validated assay on an ongoing basis.
- If the laboratory cannot satisfy this criterion, it should not perform HER2 testing and send specimens to a reference laboratory.
- Equivocal cases are not expected to be 95% concordant; they should be subjected to a confirmatory test.
