CD274 and squamous cell carcinoma: DFS benefit was observed in EGFR-negative (HR: 0.75, 95% CI: 0.62–0.91, I2 = 0%), EGFR status unknown (HR: 0.78, 95% CI: 0.63–0.96, I2 = 0%), programmed cell death ligand 1 (PD-L1) 1–49% (HR: 0.75, 95% CI: 0.58–0.97, I2 = 7.13%), non-squamous cell carcinoma (HR: 0.72, 95% CI: 0.61–0.84, I2 = 0%), and never-smoking (HR: 0.68, 95% CI: 0.49–0.96, I2 = 0%) subgroups.