Evaluation of the Updated 2022 Lung-GPA in NSCLC Adenocarcinoma Patients with Brain Metastases: Analysis of Prognostic Factors in a German Clinical Cohort

Background Lung cancer is the most frequent source of brain metastases (BMs), with 20–40% of patients with non-small cell lung cancer (NSCLC) developing BMs during their disease. The NSCLC-GPA (Graded Prognostic Assessment), developed by Sperduto et al., aims to estimate overall survival (OS) for lung cancer patients with BMs based on a variety of prognostic factors. This study aimed to validate the applicability and prognostic relevance of the 2022 updated NSCLC-GPA in a German clinical cohort, with particular attention to Programmed death-ligand 1 (PD-L1) expression and treatment-related outcomes. Methods We retrospectively analyzed NSCLC patients with BMs treated between 2020 and 2022 at a German university hospital. GPA scores were calculated using established parameters: age, Karnofsky Performance Status (KPS), number of BMs, presence of extracranial metastases (ECM), EGFR and ALK mutation status, and PD-L1 expression. Due to low numbers of non-adenocarcinoma (NAC) cases, only patients with adenocarcinoma (AC) were included. Univariate and multivariate Cox regression models, log-rank tests, and Kaplan-Meier curves for illustrative purposes were applied to evaluate associations between prognostic factors and OS. Results A total of 110 AC patients met the inclusion criteria. The median OS was 10 months (range: 6–11). Patients with GPA scores of 0–1 and 1.5–2 had significantly worse outcomes compared to the reference group (GPA 3.5–4; median OS: 36 months), with median OS of 3 and 8 months, respectively (HR: 8.34 and 5.24; p = 0.0005 and p = 0.0067). Patients with a GPA of 2.5–3 had a median OS of 22.5 months, which was not statistically significant. Older age (≥70 years; HR: 1.95, 95% CI: 1.23–3.11), low KPS (KPS ≤70; HR: 3.88, p < 0.0001), higher number of BMs (HR: 2.62, 95% CI: 1.66–4.13), and presence ECM (HR: 2.62, 95% CI: 1.66–4.13, p < 0.0001) were all significantly associated with decreased OS. In the multivariate analysis, both low KPS and ECM remained significant independent prognostic factors. PD-L1 expression showed no significant association with OS. Conclusion Despite lower OS times in our cohort, the 2022 NSCLC-GPA proved to be a valuable prognostic tool, with lower scores clearly linked to poorer outcomes. Additionally, older age, low KPS, ECM and a higher number of BMs emerged as independent prognostic factors.