What is HER2-positive breast cancer?

Updated: Jul 16, 2020
  • Author: Maurie Markman, MD, MS; Chief Editor: Karl S Roth, MD  more...
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ERBB2 is a transmembrane tyrosine kinase receptor and a member of the ErbB protein family, more commonly known as the epidermal growth factor receptor (EGFR) family. ERBB2 is most commonly known as HER2 and sometimes as also NEU. For this article, it will be referred to as HER2. Activation of this class of cellular receptors is known to result in increased activity of a variety of molecular pathways associated with tumor growth and progression. HER2 gene product is overexpressed in 18-20% of invasive breast cancers, which has both prognostic and predictive implications.

Before the routine use of trastuzumab (Herceptin, a monoclonal antibody) in adjuvant therapy, HER2 overexpression was associated with a more aggressive tumor phenotype and worse prognosis (higher rate of recurrence and mortality), independent of other clinical features (eg, age, stage, tumor grade), especially in patients who did not receive adjuvant chemotherapy.

Additionally, HER2 status has been shown to be predictive for response to certain chemotherapeutic agents (ie, doxorubicin [Adriamycin]; and HER2-targeted therapies trastuzumab, pertuzumab, and lapatinib [Tykerb, a small-molecule oral tyrosine kinase inhibitor directed specifically to the HER2 receptor]).

Retrospectively analyzed results from clinical trials have shown that HER2-positive patients benefit from anthracycline-based regimens secondary to the co-amplification of topoisomerase II with HER2. Preliminary data also suggest that HER2 may predict response to and benefit from paclitaxel in the adjuvant setting.

Go to Breast Cancer for complete information on this topic.

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