Recommendations

To improve the accuracy of HER2 testing, ASCO and CAP recommend the following:

• The HER2 status should be determined for each patient with invasive breast cancer.
• IHC and FISH tests are the only FDA-approved methods for HER2 testing. Either test may be used, as long as it is correctly performed, validated, and reproducible.
• The values for positive and negative test results must be clearly defined. A positive test result means that the tumor has high levels of the HER2 protein or an increased number of gene copies, while a negative test result means that the tumor does not. Test results that are not clearly positive or negative should be called "equivocal," which requires a repeat of the test and/or the use of a different test for further evaluation.
• The pathology laboratories that perform HER2 testing should follow specific testing procedures and handle tissue samples consistently.
• The pathology laboratories that perform HER2 testing are required to show 95% concordance (agreement) with another validated HER2 test for both positive and negative results, participate in ongoing internal and external quality assurance procedures, and hold current accreditation by a valid accrediting agency. (All accredited laboratories undergo an onsite inspection once every two years, participate in ongoing quality assurance activities, and have a valid Clinical Laboratory Improvement Act (CLIA) certificate or equivalent state license if the laboratory operates in New York or Washington State.)