ESR1 and neoplasm: The molecular makers measured in this study include estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor 2 (HER2), P-glycoprotein (P-gp), multidrug resistance-related protein (MRP), glutathione S-transferase pi (GST-pi) and topoisomerase-II (Topo-II), based on their potential roles in modulating tumor biology and sensitivity or resistance to anticancer treatments [14-16].