The multivariate model incorporated variables with P < 0.1 from the univariate analysis, and other clinically relevant covariates, revealed SCLC histology (HR = 2.01, 95% CI: 1.08–3.77, P = 0.029) emerged as an independent adverse prognostic factor for OS, while PD-L1 positive expression (HR = 0.74, 95% CI: 0.57–0.95, P = 0.017) remained an independent protective factor. This evidence concerns the gene CD274 and small cell lung carcinoma.