NEW YORK (Reuters Health) - Updated recommendations say all breast cancers should be tested for human epidermal growth factor receptor 2 (HER2) expression, and use of HER2-targeting drugs should be emphasized.
The recommendations were published jointly online October 7 by the American Society of Clinical Oncology and the College of American Pathologists, in the Journal of Clinical Oncology.
The last set of recommendations from the two groups on how to use HER2 was issued in 2007. This is the first major update.
"Besides the stringent requirements for all patients to have their tumors tested for HER2, the other main difference is the guidance for treatment even when HER2 expression occurs at very low/equivocal levels," said Dr. Kimberly Blackwell, a breast cancer specialist at Duke University Medical Center, in an email. She was not on the panel that made the recommendations.
The new advice addresses how oncologists should respond when results are equivocal. Specifically, reflex testing should be done using either immunohistochemistry or in situ hybridization if the initial HER2 test was equivocal. Repeat HER2 testing should also be considered if the initial results seem discordant with other histopathologic findings.
Even if the results are ultimately equivocal, oncologists may still consider HER2-targeted therapy, the authors say.
Previously, inaccurate test results-which could either deny a beneficial therapy to a patient who needed it or overtreat one who did not need it--were a significant concern. But improved testing methods allow for more confidence in recommending specific treatments and dealing with less common clinical scenarios, said lead author Dr. Antonio C. Wolff of Johns Hopkins Sidney Kimmel Comprehensive Cancer Center in Baltimore, in an email to Reuters Health.
"A key feature of the 2013 ASCO/CAP HER2 testing guideline update is our ability to better discriminate between HER2-positive and negative results, thereby reducing the frequency of equivocal or inconclusive test results," said Dr. Wolff. "Consequently, we were able to expand our focus beyond earlier concerns about false-positive test results."
Since the initial treatment recommendations, clinical trials have shown that HER2-targeting drugs like lapatinib, pertuzumab and T-DM1 are beneficial for HER2-positive breast cancer. However they offer no clinical benefit in HER2-negative disease and are expensive and potentially toxic for patients.
"The current guidelines place emphasis on minimizing the risk of a false negative, which results in a patient not receiving HER2-targeted therapy who might have derived substantial benefits from such therapy," said Dr. Charles Geyer, Jr., of the Virginia Commonwealth University Massey Cancer Center, in an email.
"In the previous guidelines there was greater emphasis on avoiding a false positive," he said.
The change, Dr. Geyer added, was based not only on improvements in the quality of testing, but also "the remarkable efficacy and safety of HER2-targeted therapies in patients with HER2 positive disease."
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