HER-2/neu as a predictive marker of response to breast cancer therapy

Amplification of the HER-2/neu (c-erbB-2) gene resulting in overexpression of the p185(HER-2) growth factor receptor occurs in similar to 25% of early stage breast cancers. HER-2/neu has been established as an important indep endent prognostic factor in early stage breast cancer in large cohorts of p atients and in cohorts with very long (30 year) follow-up duration. New dat a are emerging to suggest that HER-2/neu may be useful not only as a progno stic factor but also as a predictive marker for projecting response to chem otherapeutics, antiestrogens, and therapeutic anti-HER-2/neu monoclonal ant ibodies. In this review we highlight recent data on HER-2/neu as a predicti ve marker of response to breast cancer therapy and discuss the clinical imp lications of this information. The difficulty in comparing results from dif ferent data sets due to the wide variety of reagents and technologies used to detect HER-2/neu amplification/overexpression in clinical specimens is a lso discussed. Finally, we report results from experimental models of HER-2 /neu overexpression which have been used in an effort to understand the rel ationship between HER-2/neu and response to chemotherapeutics and antiestro gens in breast cancer.