CD274 and breast cancer: PDL1 expression was analyzed in 5,454 clinical breast cancer samples pooled from 18 data sets (Supplementary Tables 2-3): 1076 tumors (20%) showed PDL1 upregulation when compared to normal breast (ratio T/NB ≥2; “PDL1-up” group), and 4378 (80%) did not show upregulation (ratio <2; “PDL1-no up” group).