In this context, there are four molecular subtypes of breast cancer: 1) luminal A (ER and/or PR positive and HER2/neu negative), 2) luminal B (ER and/or PR positive and HER2/neu positive), 3) HER2-positive (ER and PR negative and HER2/neu positive), and 4) triple-negative (ER, PR, and HER2/neu negative) (Patel et al., 2020; Doğan et al., 2023). The gene discussed is ESR1; the disease is breast cancer.