CD274 and non-small cell lung carcinoma: We further reviewed the full texts of the remaining 47 studies for eligibility and excluded 21 with the following reasons: survival outcomes not investigated (n=5), non-ICI treatments (n=6), various treatments including ICIs (n=2), ICIs treatment unknown (n=2), no NSCLC patients (n=1), survival results not provided (n=3), survival analysis at specimen level (n=1), PD-L1 mRNA expression in exosomes (n=1).