CD274 and small cell lung carcinoma: PD‐L1 positivity was associated with lower lung cancer‐specific (log‐rank, P = 0.022) and overall (log‐rank, P = 0.0063) mortality in SCLC patients, whereas it showed a tendency of lower lung cancer‐specific (log‐rank, P = 0.29) and overall (log‐rank, P = 0.17) mortality in LCNEC patients.