CD274 and medical procedure: Accordingly, we stratified the TMA lung SCC cases into PD-L1 protein expression high (proportion of tumor cells expressing PD-L1 > 0.00; n = 147) and protein expression low (proportion of tumor cells expressing PD-L1 = 0.00; n = 260) groups, and formally tested for a statistical interaction between PD-L1 protein expression (high versus low) and the SI score in a CPH survival model.