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Updated Guideline Issued for HER2 Testing in Breast Cancer
The College of American Pathologists (CAP) and the American Society of Clinical Oncology (ASCO) have issued a joint, updated guideline aimed at improving the accuracy and reporting of human epidermal growth factor receptor 2 (HER2) testing in patients with invasive breast cancer.
The guideline update provides oncologists and pathologists with detailed recommendations for how to test for HER2 overexpression, interpret the results, and recommend HER2-targeted therapies. The updated guideline, originally issued in 2007, was published online in the CAP’s Archives of Pathology & Laboratory Medicine and in ASCO’s Journal of Clinical Oncology.
The guideline recommends the following:
- Always test HER2 status on all newly diagnosed invasive breast cancers (primary site and/or metastatic site).
- Ensure that at least one tumor sample is tested for either HER2 protein expression (immunohistochemistry [IHC] assay or in situ hybridization [ISH] assay) or HER2 gene amplification.
- Discuss the role of HER2-targeted therapy if the HER2 test result is positive and if there is no apparent histopathologic discordance with HER2 testing.
- Delay the decision to recommend HER2-targeted therapy if the HER2 test result is equivocal. Mandatory retesting should be done on the same specimen using the alternative test if the initial HER2 test result is equivocal or on an alternative specimen.
- Do not administer HER2-targeted therapy if the HER2 test result is negative. If there is apparent histopathologic discordance with the HER2 test result, additional HER2 testing should be considered.
- Report a HER2 test result as indeterminate if technical issues prevent one or both tests (IHC and ISH) from being done in a tumor specimen, or prevent the test (or tests) from being reported as positive, negative, or equivocal.
- Confirm that the testing laboratory conforms to standards set for accreditation by CAP or an equivalent accreditation authority.
Source: CAP; October 7, 2013.