Skov BG, et al. - Researchers evaluated the prevalence of programmed death-ligand-1 (PD-L1) positivity in individuals with non-small cell lung cancer, examined the correlation between PD-L1 positivity and individuals’ clinicopathological features, and to judge the use of immune-oncologic treatment in the eligible individuals. Eight hundred and nineteen individuals got diagnosed with non-small cell lung cancer. From 97% of individuals, samples analyzable for PD-L1 expression were achieved. With an odds ratio of 0.31 for stage I vs stage IV, the lower stage was related to a lower prevalence of PD-L1 positivity in multivariate analysis with a cut-off at tumor proportion score ≥ 50%. With the odds ratio for adenocarcinoma 1.8, a notable variation in PD-L1 expression was noted between squamous-cell carcinoma and adenocarcinoma. Attenuated impacts of the same direction were observed with a cut-off tumor proportion score of ≥ 1%. For neither cut-off did the type and location of material utilized for PD-L1 analysis, age, sex, smoking history, or performance status have a statistically important influence on the PD-L1 expression. In the first-line with pembrolizumab monotherapy, 54% of the individuals who were eligible for immune-oncologic treatment were truly treated. Therefore, for PD-L1, 97% of the individuals had material analyzable. A negative or low positive PD-L1 test performed on a biopsy taken in a lower stage might not reflect the PD-L1 expression in the new metastatic lesion if an individual in need of immuno-oncologic treatment has shifted stage. Thus, a re-biopsy should be thought about.