On multivariate analysis, after adjusting for gender and smoking status, heavy smoking and EGFR wild-type tumors remained significantly associated with high PD-L1 expression in NSCLCs and also in adenocarcinoma.<h4>Conclusions</h4>Heavy smoking and EGFR wild-type tumors were significantly associated with high PD-L1 expression in NSCLCs and also in adenocarcinoma. Here, CD274 is linked to adenocarcinoma.