Although the majority (~75%) of endometrial tumors are of endometrioid histology (designated type I tumors), expressing high levels of estrogen receptor (ER), progesterone receptor (PR), and epidermal growth factor receptor (EGFR), about 25% of tumors are of advanced stage (designated type II tumors), are unlikely to be ER+/PR+, and have a poorer prognosis [1]. Here, ESR1 is linked to endometrium neoplasm.