ESR1 and neoplasm: A recent study has found that increasing ER percentage is associated with a lower likelihood of tumor downstage and pCR at surgery among patients who receive NACT.18 In the era of precision medicine, incorporating quantitative assessments of ER, PR, and Ki-67 expression, the 21-gene RS, or the 70-gene risk scores could help clinicians identify and further classify patient groups with regard to tumor response and neoadjuvant treatment selection as well as subsequent BCS.