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Guideline recommends HER-2 testing for all invasive breast cancers

ASCO and the College of American Pathologists issued a joint guideline that recommends all patients with newly diagnosed invasive breast cancer be tested for HER-2 status to help guide treatment decisions.

The recommendation suggests at least one tumor sample is tested through an immunohistochemistry assay or in situ hybridization assay. If the results of one test are equivocal, a subsequent test should be performed using the alternate assay.

About 15% of all newly diagnosed breast cancers are HER-2 positive, and those tumors tend to grow faster than HER-2–negative tumors. Testing can help identify patients who may benefit from targeted therapies that can extend survival.

 

Antonio C. Wolff

“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,” Antonio C. Wolff, MD, FAC, FASCO, co-chair of the ASCO and College of American Pathologists HER-2 Testing in Breast Cancer Panel and professor of oncology at Johns Hopkins Kimmel Comprehensive Cancer Center, said in a press release. “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.”

The guideline also recommends clinicians:

• Discuss the role of HER-2– targeted therapy if test results are positive and there is no apparent histopathologic discordance with HER-2 testing.
• Delay recommendations for HER-2–targeted therapy if tests are equivocal.
• Do not administer HER-2–targeted therapy if test results are negative.
• Repeat testing if results do not reflect histopathologic findings.

The guideline — which establishes HER-2–positivity can be determined after immunohistochemistry indicates protein expression in more than 10% of tumor cells — is an update to 2007 guidelines that defined HER-2 positivity as expression in more than 30% of tumor cells. The original recommendation reflected the concern for false-positive results, which recent data suggest are no longer as prevalent.

“The number of patients with equivocal HER-2 test results used to be rather large, but evidence suggests that the quality of HER-2 testing is improving and the frequency of equivocal and inaccurate results is decreasing,” M. Elizabeth H. Hammond, MD, FCAP, co-chair of the guideline panel and professor of pathology at the University of Utah School of Medicine, said in the press release. “We believe that this is at least in part due to our earlier recommendations in 2007. We hope the current guideline will resolve remaining challenges in the field, and ultimately result in better outcomes for all patients with breast cancer.”

Disclosure: Researchers report employment, leadership, consultant or advisory roles with, as well as honoraria, research funding or other remuneration from, Abbott, Dako, GE Healthcare, Genomic Health, Roche, Roche Canada and Roche UK.