ESR1 and breast cancer: Then, by using qRT-PCR, we aimed to examine the levels of expression for five miRNAs in the serum of healthy individuals as well as BC patients, including (a) different stages; early and late stages, and (b) three diverse receptor statuses; ER positivity (ER + ve& HER-2 -ve), HER2 positivity (HER + ve & ER -ve), and the TNBC subtype.