ASCO and the College of American Pathologists Issue Updated Guideline on HER2 Testing in Breast Cancer
ASCO and the College of American Pathologists (CAP) today issued a joint, updated guideline to improve the accuracy and reporting of human epidermal growth factor receptor 2 (HER2) testing in patients with invasive breast cancer. The six-recommendation guideline is based on a systematic review of medical research literature, and provides oncologists and pathologists with detailed recommendations for how to test for HER2 overexpression, interpret the results, and recommend HER2-targeted therapies. The guideline, originally issued in 2007, is published in ASCO’s Journal of Clinical Oncology (JCO) and the CAP’s Archives of Pathology & Laboratory Medicine.
Key Recommendations
The joint guideline was prepared by an ASCO/CAP Update Committee, which included experts in breast cancer and cancer biomarkers. The Committee’s recommendations include:
- 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 (by immunohistochemistry assay) or for HER2 gene amplification (by in situ hybridization assay).
- 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 (immunohistochemistry and in situ hybridization) 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.
According to the joint statement released by ASCO and CAP, “In rare cases, it may be difficult to know for sure if the result is positive or negative. If additional testing on other tissue specimens is not possible, pathologists and oncologists should consider all available clinical data on the patient prior to recommending HER2-targeted therapy.”
Determining Patients Most Likely to Benefit From HER2-Targeted Therapy
Since approximately 15% of all newly diagnosed breast cancers are HER2-positive, the purpose of HER2 testing is to identify patients who could benefit most from effective HER2-targeted therapy—such as trastuzumab (Herceptin), lapatinib (Tykerb), pertuzumab (Perjeta), and ado-trastuzumab emtansine (Kadcyla)—while sparing patients who are unlikely to benefit the side effects and costs associated with these drugs.
“Our ability to identify cancer subtypes that will lead to more individualized therapeutic decisions and that are shown to improve clinical outcomes is rapidly improving,” said Antonio C. Wolff, MD, FACP, FASCO, Co-Chair of the ASCO/CAP HER2 Testing in Breast Cancer Panel and Professor of Oncology at the Johns Hopkins Kimmel Comprehensive Cancer Center, in a statement. “Consequently, and more than ever before, society must demand access to high-quality cancer biomarker tests that can help cancer specialists match the right treatments with the right patients. This guideline update strengthens and clarifies recommendations for HER2 testing based on new evidence.”
Additional Tools and Resources
In conjunction with publication of the guideline, ASCO and CAP have developed clinical tools and resources for oncologists and pathologists that summarize the findings and recommendations. The resources include supplemental information on clinical questions, as well as immunohistochemistry and in situ hybridization test result interpretation criteria and reporting elements. ASCO and CAP have also developed a companion patient guide, available on both Cancer.Net and www.cap.org.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
