PDCD1 and neoplasm: Based on standard uptake values (SUV), tumor metabolic volume (MTV), and tumor glycolysis (TLG) determined by 18F-fluoro-2-deoxyglucose (18F-FDG) positron emission tomography (PET), they are associated with high levels of PD-L1 and the expression of PD-1, CD8, CD163 (tumor-associated macrophages), and Foxp3 (Tregs) TILs (tumor-infiltrating lymphocytes), suggesting the potential of metabolic parameters as prognostic biomarkers (Castello et al. 2020; Takada et al. 2017).