In recent years, whole-genome gene expression profiling based on expression of estrogen receptor alpha (ERα), progesterone receptor (PR) or the human epidermal growth factor receptor 2 (HER2) has allowed to evaluate the prognosis and apply targeted treatment strategy of patients with BC, but long-term survival is still not optimistic due to frequent recurrence and metastasis [2–4]. The gene discussed is ESR1; the disease is breast cancer.