Her-2/neu as predictive marker for endocrine therapy and chemotherapy in patients with metastatic breast cancer

While expression of estrogen receptor (ER) and/or progesterone receptor (PgR) predict for the efficacy of endocrine therapy and Her-2/neu overexpression/amplification predict (imperfectly) for the efficacy of treatment with trastuzumab, neither of these markers has proved effective at predicting antitumor response to other therapies. Overexpression/amplification of Her-2/neu has been one of the most extensively studied predictive parameters, but results have been controversial. In the present article we attempt to review articles published in peer-reviewed medical journals to summarize the evidence concerning Her-2/neu as a predictive factor for the efficacy of endocrine and chemotherapy, respectively. In addition, general limitations of published studies, encouraged and discouraged practices resulting from the available data and future directions which will clarify the role of Her-2/neu as a predictive parameter will be discussed.