The College of American Pathologists (CAP) and the American Society of Clinical Oncology (ASCO) have published updated guidelines on human epidermal growth factor receptor 2 (HER2) testing in patients with invasive breast cancer in an early online release in the CAP’s Archives of Pathology & Laboratory Medicine and ASCO’s Journal of Clinical Oncology (JCO).

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The update is based on a systematic review of medical research literature and provides detailed recommendations for how to test for HER2 overexpression, interpret the results, and recommend targeted therapies. 

It emphasizes the importance of accurately determining HER2 status in order to medicate patients with individualized HER2-targeted therapies, such as trastuzumab (Herceptin; Genentech), lapatinib (Tykerb; GlaxoSmithKline), pertuzumab (Perjeta; Genentech), and T-DM1 (Kadcyla; Genentech).

The guidelines strengthen recommendations based on a new diagnostic technique known as bright-field ISH, a technique involving a regular light microscope to evaluate for amplification of the HER2 gene. 

The new recommendations state that all newly diagnosed invasive breast cancer patients should be tested for HER2 status and to delay HER2-targeted therapy if the HER2 test result is equivocal. Further, any test results that are equivocal should be retested on a mandatory basis.

Updated guidelines also include recommendations on key points for doctors to discuss with patients, and place an emphasis on close collaboration by the entire healthcare system to give patients the best therapy possible.

In addition to the guideline publication, CAP and ASCO have developed clinical tools and resources for pathologists and oncologists that summarize the findings and recommendations.

For more information call (800) 323-4040 or read the ASCO Guidelines