The majority of this research has been performed in breast cancer tissue on estrogen receptor, progesterone receptor (Turbin et al., 2008; Faratian et al., 2009; Bolton et al., 2010; Krecsak et al., 2011), human epidermal growth factor receptor (Atkinson et al., 2011; Ayad et al., 2015), Ki 67 assessment in breast cancer (Ayad et al., 2018). The gene discussed is ESR1; the disease is breast cancer.