Test Details: Immunohistochemical testing is carried out on biopsy/resected tissue specimen. This testing helps to identify specific antigens (proteins) within tissue sections utilizing an antigen-specific antibody .Human epidermal growth factor receptor-2 (HER-2), also known as p185, ERBB-2, or c-erbB-2 (chicken erythroblastic viral oncogene homolog 2), is one of the four members of the epidermal growth factor receptor family clustered as CD340. The overexpression of HER-2 is characteristic for few types of human carcinomas, mainly breast and gastric adenocarcinomas in addition to a subset of other carcinoma types such as ovarian carcinoma, non-small cell carcinoma of the lung and salivary gland carcinoma, and urinary bladder transitional cell carcinoma. Over-expression of HER2/neu is associated with poor prognosis of breast, ovarian, bladder, pancreatic, stomach, and oesophageal malignancies. It predicts for a positive response to a monoclonal antibody, trastuzumab, targeted against the HER2/neu receptor.