ESR1 and cancer: EPC usually express a luminal phenotype, that positive for ER and progesterone receptor but negative for HER2.[13] Ki-67 has been used as a routine detection index for the diagnosis, prognosis and postoperative treatment of a variety of malignant tumors.[14] It is commonly known that the high expression of Ki-67 is related to the increased risk of recurrence and poor prognosis.