Stage I–III BC patients were 78.4% ER+/21.6% ER− and 68.1% PR+/31.9% PR− [184], and stage IV BC patients were 71.3% ER+/28.7% ER− and 68.0% PR+/32% PR−, according to the data from the SEER database [185]. The gene discussed is ESR1; the disease is breast cancer.