We confirmed these results in the Validation Cohort of 549 primary breast tumors (r = −0.51 and r = −0.62 respectively, Spearman correlation test, p < 0.0001; ROC curves for KI67: AUC = 0.74, SE = 0.02, 95% CI = 0.707 to 0.788, and for CD44: AUC = 0.81, SE = 0.01, 95% CI = 0.776 to 0.848, p < 0.0001) (Figure 4B). This evidence concerns the gene CD44 and breast neoplasm.