New guidelines for HER2 testing

This review and guideline update examined the role of human epidermal growth factor receptor 2 (HER2) testing in breast cancer patients.

Human epidermal growth factor receptor 2 (HER2) is a structure on the surface of some cells that stimulates cell growth.  Overexpression (overproduction) of this protein may lead to aggressive growth and is believed to be the cause of 15% to 20% of breast cancers. Although cancers tested positive for high levels of HER2 tend to grow and spread more rapidly, patients also benefit from therapies that directly target and inhibit the actions of this structure. The first guidelines for HER2 testing were published in 2007. This expert review by the American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) analyzed recent research to reach updated recommendations and guidelines regarding HER2 testing for breast cancer patients.

Expert recommendations based on a review of recent evidence state that all new and recurrent cases of breast cancer must be evaluated for HER2 status. New findings indicate that recurring tumors after cancer treatments and new tumors arising from the spread of the cancer (metastasis) may possess a different HER2 status than the original cancer. Therefore, if the cancer has metastasized (spread to other organs), each tumor site should be tested separately.

A sample for HER2 testing should be obtained by a core needle biopsy (taking a sample from the center of the tumor using a needle). If results of HER2 testing are unclear or not definitive, a section of the tumor removed during surgery should also be tested to limit the chances of false results.

Consult with your physician regarding the implications of HER2 status on breast cancer treatments.