In the management of early-stage non-small cell lung cancer (eNSCLC), the introduction of PD-1/PD-L1 checkpoint inhibitors has marked a significant advancement. While PD-L1 is a crucial biomarker, its role in eNSCLC remains ambiguous. Additionally, PD-L1 is closely linked to glucose transporter 1 (GLUT1) expression, and the correlation of metabolic parameters measured using [18F] FDG-PET/CT has been established in advanced disease. This study aimed to explore the association between [18F] FDG-PET/CT metabolic parameters and PD-L1 expression in a cohort of patients with resected early-stage NSCLC. A retrospective analysis of 210 patients with node-positive early-stage resected NSCLC was conducted. PD-L1 immunohistochemistry using DAKO 22C3 was performed on primary tumors and positive nodes, scored based on the tumor proportion score (TPS) of <1, 1-49, or ≥50%. [18F]FDG PET/CT was analyzed for max, mean, and peak standardized uptake values (SUV), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and SUV heterogeneity index (HISUV) using semi-automated techniques. The results showed that PD-L1 TPS was associated with increased mean SUVmax scores of the primary tumor and nodes. Similar trends were observed for mean SUVmean and SUVpeak values across all TPS groups. While SUVmax, mean, and peak scores were significantly associated with PD-L1 positivity using a <1% or ≥1% threshold, the sensitivity and specificity of these measurements for predicting PD-L1 positivity were found to be poor. ROC analysis demonstrated only moderate separability. In conclusion, this study revealed an association between [18F]FDG PET/CT metabolic parameters and PD-L1 expression in early NSCLC. However, the effectiveness of these measurements in predicting PD-L1 positivity using a specific threshold was limited, emphasizing the need for future prospective studies to determine their association, predictive role, and clinical utility.
