Evaluation of HER2/neu oncoprotein in serum and tissue samples of women with breast cancer: correlation with clinicopathological parameters.

Background: HER2/neu (HER2) is a proto-oncogen of the EGF Receptor family. The assessment of serum HER2 level is useful for predicting the patients' response to chemotherapy or hormonal therapy and selection of proper patients for treatment with Herceptin. We aimed to compare serum HER2 levels with immunohistochemistry in tumoral tissues and investigate correlation between these levels and various prognostic factors.