After adjustment for confounders including age, menopausal status, BMI, histology, grade, ER, PR, HER-2 expression, tumor size, node status, clinical stage and comorbidity, anemia remained indicative of decreased likelihood of pCR (odds ratio (OR) 0.428, 95% confidence interval (CI) 0.198–0.927, p = 0.031). Here, ESR1 is linked to anemia (phenotype).