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 .Estrogen receptors (ER) are a member of the steroid family of ligand dependent transcription factors and include two types encoded by two different genes on different chromosomes, the alpha type (ER-α) and beta type (ER-β). Estrogen and progesterone play key roles 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 independently of hormonal treatment.