Early Online Release

Recommendations for Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer: American Society of Clinical Oncology/College of American Pathologists Clinical Practice Guideline Update

Antonio C. Wolff *, M. Elizabeth H. Hammond *, David G. Hicks *, Mitch Dowsett *, Lisa M. McShane *, Kimberly H. Allison, Donald C. Allred, John M.S. Bartlett, Michael Bilous, Patrick Fitzgibbons, Wedad Hanna, Robert B. Jenkins, Pamela B. Mangu,Soonmyung Paik, Edith A. Perez, Michael F. Press, Patricia A. Spears, Gail H. Vance, Giuseppe Viale, and Daniel F. Hayes *

Antonio C. Wolff, Johns Hopkins Kimmel Comprehensive Cancer Center, Baltimore; Lisa M. McShane, National Cancer Institute, Bethesda, MD; M. Elizabeth H. Hammond, University of Utah School of Medicine and Intermountain Healthcare, Salt Lake City, UT; David G. Hicks, University of Rochester Medical Center, Rochester, NY; Mitch Dowsett, Royal Marsden Hospital, London, United Kingdom; Kimberly H. Allison, Stanford University Medical Center, Stanford; Patrick Fitzgibbons, St Jude Medical Center, Fullerton; Michael F. Press, University of Southern California, Los Angeles, CA; Donald C. Allred, Washington University School of Medicine, St Louis, MO; John M.S. Bartlett, Ontario Institute for Cancer Research; Wedad Hanna, Sunnybrook Health Sciences Center, Toronto, Ontario, Canada; Michael Bilous, University of Western Sydney and Healthscope Pathology, Sydney, New South Wales, Australia; Robert B. Jenkins, Mayo Clinic, Rochester, MN; Pamela B. Mangu, American Society of Clinical Oncology, Alexandria, VA; Soonmyung Paik, National Surgical Adjuvant Breast and Bowel Project, Pitsburgh, PA; Edith A. Perez, Mayo Clinic, Jacksonville, FL; Patricia A. Spears, North Carolina State University, Raleigh, NC; Gail H. Vance, Indiana University Medical Center, Indianapolis, IN; Giuseppe Viale, University of Milan, European Institute of Oncology, Milan, Italy; and Daniel F. Hayes, University of Michigan Comprehensive Cancer Care Center, Ann Arbor, MI.

Purpose. To update the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guideline recommendations for human epidermal growth factor receptor 2 (HER2) testing in breast cancer to improve the accuracy of HER2 testing and its utility as a predictive marker in invasive breast cancer.

Methods. ASCO/CAP convened an Update Committee that included coauthors of the 2007 guideline to conduct a systematic literature review and update recommendations for optimal HER2 testing.

Results. The Update Committee identified criteria and areas requiring clarification to improve the accuracy of HER2 testing by immunohistochemistry (IHC) or in situ hybridization (ISH). The guideline was reviewed and approved by both organizations.

Recommendations. The Update Committee recommends that HER2 status (HER2 negative or positive) be determined in all patients with invasive (early stage or recurrence) breast cancer on the basis of one or more HER2 test results (negative, equivocal, or positive). Testing criteria define HER2-positive status when (on observing within an area of tumor that amounts to >10% of contiguous and homogeneous tumor cells) there is evidence of protein overexpression (IHC) or gene amplification (HER2 copy number or HER2/CEP17 ratio by ISH based on counting at least 20 cells within the area). If results are equivocal (revised criteria), reflex testing should be performed using an alternative assay (IHC or ISH). Repeat testing should be considered if results seem discordant with other histopathologic findings. Laboratories should demonstrate high concordance with a validated HER2 test on a sufficiently large and representative set of specimens. Testing must be performed in a laboratory accredited by CAP or another accrediting entity. The Update Committee urges providers and health systems to cooperate to ensure the highest quality testing.