Correlation of tumor-related immunity with 18F-FDG-PET in pulmonary squamous-cell carcinoma

Abstract Objectives 2-Deoxy-2-[fluorine-18] fluoro- d -glucose with positron emission tomography ( 18 F-FDG-PET) is a clinically useful tool for cancer evaluation. 18 F-FDG accumulation in tumor cells is known to be correlated with the presence of glucose transporter 1 (GLUT1) and hypoxia-inducible factor-1α (HIF-1α). Although anti-programmed death-1 (PD-1) antibody treatments have been approved, no suitable predictor of significant responders has been identified. Based on the existing information, we investigated the relationship between tumor immunity (including PD-L1) and 18 F-FDG uptake in patients with surgically resected pulmonary squamous-cell carcinoma (SQC). Materials and methods This study included 167 patients (153 men and 14 women) with SQC who underwent 18 F-FDG PET. Tumor sections were stained by immunohistochemistry for GLUT1, HIF-1α, PD-L1, CD4, CD8, and Foxp3. The relationship between clinicopathological features and 18 F-FDG uptake was analyzed. Student’s t -test, the χ 2 test, non-parametric Spearman’s rank test and the Kaplan–Meier method were used to show associations between variables. Results The rate of positive PD-L1 expression was 79% (132/167), and PD-L1 expression was significantly associated with GLUT1 ( P   0.01), HIF-1α ( P   10 −4 ), and CD8 ( P   1 × 10 −3 ) expression. The SUV max of 18 F-FDG was significantly correlated with PD-L1 ( P  = 0.02) and GLUT1 ( P   0.01) expression. Multivariate analysis demonstrated that advanced stage, elevated PD-L1 expression, and elevated SUV max were independent prognostic factors for predicting poor OS. Among patients with a high SUV max , multivariate analysis confirmed that advanced stage and high PD-L1 expression were independent prognostic factors for poor OS; however, there was no significant difference among patients with a low SUV max . Conclusion High SUV max on 18 F-FDG-PET is associated with PD-L1 expression but is an independent prognostic factor for OS in our population of surgically resected pulmonary squamous-cell carcinoma.