ESR1 and breast cancer: Our results showed that the sensitivity and specificity of strong positive fascin‐1 expression for predicting TNBC were 78.0% and 96.5% in all cases of breast cancer, 78.0% and 92.6% in hormone receptor–negative cases of breast cancer, and 71.4% and 90.0% in cases of breast cancer with ER−, PR−, and HER2 2+ equivocal status who underwent FISH, respectively.