ESR1 and neoplasm: The tumor markers with certain clinical utility include CA 15-3, CA 27.29, carcinoembryonic antigen (CEA), estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), urokinase plasminogen activator (uPA), plasminogen activator inhibitor 1 (PAI-1), and multiparameter gene expression assays [6].