Background Pembrolizumab monotherapy is an established front-line treatment for advanced non-small cell lung cancer (NSCLC) with programmed cell death-ligand 1 (PD-L1) tumor proportion score (TPS)≥50%. However, real-world data on its long-term efficacy remains sparse. Methods This study assessed 5-year outcomes of first-line pembrolizumab monotherapy in a large, multicenter, real-world cohort of patients with advanced NSCLC and PD-L1 TPS≥50%, referred to as Pembro-real 5Y. Individual patient-level data (IPD) from the experimental arm of the KEYNOTE-024 trial were extracted (KN024 IPD cohort) to compare the long-term outcomes between the two cohorts. To further assess the reproducibility of clinical trial results, we reconstructed the “KN024 look-alike” cohort by excluding patients with an Eastern Cooperative Oncology Group-performance status (ECOG-PS)≥2, those requiring corticosteroids with doses ≥10 mg of prednisolone/equivalent, patients with positive/unknown epidermal growth factor