Figure 8. Receiver operating characteristic curve of the data used in Figure 7 in order to determine the optimum cut-off for von Willebrand factor (VWF) mRNA expression above which the Prosigna Breast Cancer Prognostic Gene Signature Assay (PAM50) subtype was probably normal and below which it was probably abnormal determine. Area under curve=0.784 (95% confidence intervaI=0.682-0.887), standard error=0.052, p<0.001. Using a cut-off of 12 sensitivity was 45%, specificity was 99%. positive predictive value=78%, negative predictive value=97% accuracy 97%.