Test Details: Amplification and overexpression of HER 2/neu gene is associated with poor prognosis in breast cancer patients. HER 2 positivity is incorporated into prognostic decision making regarding adjuvant systemic therapy. HER 2 status is predictive for relative resistance and response to endocrine therapies and chemotherapy drugs. HER 2/neu protein overexpressing tumours are amenable to targeted treatment with monoclonal antibody Herceptin and show increased sensitivity to anthracyclines.