In the first-line treatment of elderly patients with advanced-stage non-small cell lung cancer (NSCLC) with high programmed death-ligand 1 (PD-L1) expression (tumor proportion score ≥ 50%), this study aimed to determine whether pembrolizumab monotherapy (MONO) or pembrolizumab plus platinum-based chemotherapy (COMB) should be selected. This evidence concerns the gene CD274 and non-small cell lung carcinoma.