Estrogen Receptor–Positive, HER-2 Nonamplified Breast Cancer

Abstract

Although histologic type provides critical insight into the behavior and natural history of breast cancer, gene expression profiling plays an important role in determining prognosis and guiding treatment selection. Tumor cells express biologically active molecules on the cell surface and within the cell that serve as receptors and rely on ligands to mediate a response to the cell. Two nuclear receptors, estrogen receptor (ER) and progesterone receptor (PR), and one cell surface receptor, human epidermal growth factor 2 receptor (HER-2), have been established as critical factors in the management of breast cancer. The first hormone receptor, ER, was identified and described in the 1960s. Advances in genomic analysis have allowed for molecular subtyping within the umbrella of hormone receptor status. Here we focus on tumors that express ER but do not express HER-2 and the relevant diagnostic workup and treatment (neoadjuvant and adjuvant) strategies. This review contains 5 figures, 5 tables, and 41 references. Key words: adjuvant therapy, breast cancer, endocrine therapy, estrogen receptor positive, HER-2 nonamplified, hormone receptors