Changes to testing guidelines have doubled the number of patients who test positive for HER2, a protein used to diagnose breast cancer, according to a study published by Mayo Clinic researchers in the Journal of Clinical Oncology.
Officials at the American Society of Clinical Oncology/College of American Pathologists recommended changes to the testing guidelines in 2013. The FDA approved the original guidelines in 1998. The latest recommendations change the cut-off for equivocal and positive cases, according to the study.
Researchers hypothesized that the new criteria set forth by the ASCO would lead to an increase in the number of breast cancer cases that tested positive for HER2. Their results showed that the new guidelines nearly doubled the number of patients testing positive for HER2, from 13 to approximately 28 percent, according to the study.
All physicians now test newly diagnosed breast cancer patients for HER2. The results provide some insight into whether women who test positive for HER2 may benefit from HER2-directed therapies. Cancers that have the HER2 molecule tend to be more aggressive and spread more quickly than other forms of breast cancer.
Patients and physicians should only consider such therapies after carefully considering the risks and benefits, according to the study.
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