Expression of Hormone Receptor Status and HER-2/neu in Breast Cancers: A Review in Various Ethnic Groups

Abstract

The role of hormone receptor status including estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor type 2 (HER-2/neu) commonly termed as ER, PR, and HER-2/neu expression in breast cancer by immunohistochemistry (IHC) is a widely accepted tool to assess prognosis as well as therapeutic management. With further standardization of the reporting template prescribed by the College of American Pathologists as "CAP Protocol" and American Society of Clinical Oncology ("ASCO guidelines"), IHC has effectively replaced cytological assays in evaluating the status of expression of hormonal receptors. The pattern of these hormonal receptors' expressions varies with regard to genetic, environment, lifestyle, and sociodemographic factors. There are well-established clinical evidences to substantiate the clinical utility of ER expression as a standard predictive biomarker to assess the prognosis of hormonal therapy. The same insight about the clinical utility of PR is questionable. However, the diagnostic utility of PR for predicting the clinical response to chemotherapy among ER-positive breast cancer patients remains unclear. This warrants future studies incorporating the integrated analysis of survival data, gene expression and its data profile, and compilation of ER and PR expressions from various large cohort analysis of breast cancer patients. This review focuses on the clinical utility and the inherent variation of the hormone receptor expression among notable diverse demographic study groups across the world.