ERα immunoreactivity was strongly positive in normal endometrium and atypical hyperplasic endometrium with a positive staining rate ranging from 93.9% to 100%, while 73.8% of endometrioid adenocarcinoma exhibited the positive immunoreactivity to ERα with a strong positive staining rate of 12.5% (Table 3). The gene discussed is ESR1; the disease is endometrioid adenocarcinoma.