Based on the hypothesis that increased malignant behaviour (higher tumour grade, positive nodal status, CTC dissemination) might be associated with PD-L1 mediated systemic immune tolerance, we measured in this study expression of 51 cytokines in the peripheral blood of BC patients with the aim to identify non-invasive, PD-L1-mediated surrogate markers of immune suppression. Here, CD274 is linked to breast cancer.