CXCL12 and breast cancer: Firstly, the presented model—using the plasma concentrations of SDF-1α, VEGF-A, sVEGFR1 and sVEGFR2 and the sVEGFR2/sVEGFR1 ratio, as well as the number of circulating EPCs, for predicting disease-free survival in breast cancer patients—may help to identify patients with poorer prognoses, who would benefit from more intense treatment.