ESR1 and breast cancer: To further screen the above variables, stepwise multiple logistic regression was then performed, which revealed that older age (OR = 1.091), higher ER expression (OR = 3.524), and higher proportion of cells expressing PR (OR = 1.027) were positively correlated with low RS in BC patients, whereas higher histologic grade (OR = 0.108) and higher proportion of cells expressing Ki‐67 (OR = 0.942) were negative predictors of low RS results.