Association between PD-L1 Expression and Metabolic Activity on ¹⁸F-FDG PET/CT in Patients with Small-sized Lung Cancer

Aim: We evaluated the metabolic characteristics of small-sized lung cancer using ¹⁸F-fluorodeoxyglucose positron-emission tomography/computed tomography (¹⁸F-FDG PET/CT) with regard to programmed cell death ligand 1 (PD-L1) expression. Materials and Methods: PD-L1 expression was evaluated by immunohistochemistry with the antibody clone SP142 in 263 patients with surgically resected primary small-sized lung cancer. Specimens with <5% tumor membrane staining were considered negative. We examined the association between the frequency of PD-L1 expression and the maximum standardized uptake value (SUVmax) in preoperative ¹⁸F-FDG PET/CT. Results: Among patients with non-small cell lung cancer (NSCLC), the SUVmax was significantly higher in those with PD-L1 expression than in those without (p<0.0001). However, there was no correlation between SUVmax and PD-L1 expression in patients with neuroendocrine tumors (p=0.9638). Multivariate analysis revealed that smoking and a high SUVmax were independent predictors of PD-L1 expression. Conclusion: PD-L1 expression was related to high glucose metabolism in small-sized NSCLC.