PDCD1 and breast cancer: Expression levels of programmed cell death protein 1 (PD-1), cytotoxic T-lymphocyte–associated antigen 4 (CTLA-4), programmed death-ligand 1 (PD-L1), Forkhead box P3 (FOXP3), miR-155, and miR-195 were assessed in the peripheral blood of 90 BC patients compared to 30 healthy controls using quantitative real-time PCR (qRt-PCR).