RFS and OS of breast cancer patients based on the differentiation tumor status. (a) Kaplan-Meier RFS and OS curves for UNC337 and NKI295 cohorts. Patients were rank-ordered and divided into two equal groups (low scores/differentiation in red and high scores/differentiation in black). (b) A combined multivariate analysis stratified by cohort was performed to test for significance of the differentiation status (as a continuous variable) conditioned on tumor intrinsic subtype, tumor size, histological grade, node status and ER. HR, hazard ratio; CI, confidence interval.