Test Details: Estrogen and progesterone play a key role in a woman's sexual development and reproductive functions. Over-expression of Estrogen receptor (ER) and Progesterone receptor (PR) is seen in tumours of female sex steroid hormone responsive tissues such as the breast, endometrium, and ovary. ER/PR status predicts response to hormonal therapy and is a prognostic marker for survival in breast cancer patients. Positive steroid hormone status has predicted favourable overall survival independent of hormonal treatment. HER2/neu is a protein involved in normal cell growth. Over-expression of HER2/neu is associated with poor prognosis of breast, ovarian, bladder, pancreatic, stomach, and oesophageal malignancies. It predicts a positive response to a monoclonal antibody, Herceptin/Trastuzumab, targeted against the HER2/neu receptor. Fluorescence in situ hybridization (FISH) is a more accurate and predictive test for HER-2/neu gene amplification as compared to immunohistochemistry. If the sample is equivocal/borderline (2+) by HER-2/neu IHC then it is further confirmed by FISH based assay. Ki67 is a nuclear protein linked to the cell cycle. It is a marker of cell proliferation. Tumours with a low Ki-67 generally means a less aggressive cancer. A low score is correlated with a better chance of survival while a high Ki-67 index is associated with poor prognosis but has a positive predictive factor for response to chemotherapy.