This challenges the currently used factors, such as lymph node involvement, tumor size, age, histological grade, human epidermal growth factor receptor 2 (HER2), Ki67, and estrogen (ER) and progesterone receptor (PgR) status (Goldhirsch et al. 2011; Aebi et al. 2011; Harris et al. 2007). The gene discussed is ESR1; the disease is neoplasm.