Real-World Treatment Outcomes and Prognostic Factors in Metastatic EGFR-Mutated Non-Small Cell Lung Cancer: A Single-Center Study from a High-Volume Tertiary Chest Hospital

Background/Objectives: Epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC) is a distinct molecular subgroup responsive to EGFR tyrosine kinase inhibitors (TKIs). This study evaluated real-world treatment outcomes and prognostic factors in patients with EGFR-mutated metastatic NSCLC. Methods: This retrospective study included 124 patients treated with first-line EGFR-TKIs between January 2017 and 30 August 2025 at a tertiary center. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan–Meier method, and prognostic factors were assessed using Cox proportional hazards models. Results: The median age was 66 years, and 63.7% of patients were female. The most common mutation was exon 19 deletion (65.3%). Median OS for the entire cohort was 31.7 months, and median PFS was 16.3 months. In multivariate analysis, Eastern Cooperative Oncology Group performance status (ECOG PS), histopathological subtype, uncommon EGFR mutations, and bone metastasis were statistically significantly associated with OS in multivariable Cox regression analysis. Among patients receiving second-line treatment, median PFS was 16.7 months with osimertinib and 4.1 months with platinum-based chemotherapy; these nonrandomized treatment-specific outcomes were considered descriptive. Conclusions: In conclusion, the survival outcomes observed in our cohort were generally consistent with previously published real-world data in EGFR-mutant metastatic NSCLC. ECOG performance status and bone metastasis were significantly associated with OS, while associations involving histopathological subtype and uncommon EGFR mutations should be considered exploratory given the small subgroup sizes and limited statistical power. These findings provide real-world evidence on treatment patterns and survival outcomes among patients with EGFR-mutant metastatic NSCLC in Türkiye.