Correlation of Fluorodeoxyglucose (FDG) PET Biomarkers (SUVmax, SUVpeak, TLG, and MTV) With Histopathological and Biochemical Parameters in FDG-Avid Lung Carcinoma

Background Lung carcinoma remains a major cause of cancer-related mortality worldwide. Fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) is a critical imaging modality in assessing tumor metabolic activity and burden. This study evaluates the correlation of FDG PET biomarkers, including maximum standardized uptake value (SUVmax), peak SUV (SUVpeak), total lesion glycolysis (TLG), and metabolic tumor volume (MTV), with histopathological and biochemical parameters in FDG-avid lung carcinoma, with a focus on tumor size, stage, and histological subtype. Methods This cross-sectional study included 45 patients diagnosed with FDG-avid lung carcinoma. FDG PET-CT imaging was performed to measure key biomarkers (SUVmax, SUVpeak, TLG, and MTV), and histopathological analysis was used to determine the tumor subtype. Biochemical markers, such as albumin, C-reactive protein (CRP), and neutrophil-to-lymphocyte ratio (NLR), were also evaluated. Correlation analyses were conducted using Pearson and Spearman tests, with multivariate regression models used to identify independent predictors of FDG uptake. Polynomial regression was employed to explore potential non-linear relationships between tumor size and FDG PET biomarkers. Results SUVmax showed a significant positive correlation with tumor size across all stages (r = 0.68, p < 0.001), with stronger associations in advanced stages (Stage II: r = 0.75, p = 0.02; Stage III: r = 0.80, p = 0.01). A strong correlation was found between TLG and MTV (r = 0.89, p < 0.001). Histological analysis revealed significantly higher SUVmax values in squamous cell carcinoma (17.4 ± 8.1) compared to adenocarcinoma (12.8 ± 6.4) (p = 0.04). Biochemical markers, including CRP and NLR, showed moderate correlations with PET biomarkers, particularly with TLG (r = 0.34, p = 0.03). Multivariate analysis revealed that tumor size and stage were significant predictors of SUVmax and TLG. Polynomial regression suggested a non-linear relationship between tumor size and FDG uptake, particularly in larger tumors. Conclusion FDG PET biomarkers, especially SUVmax, TLG, and MTV, provide valuable prognostic information in lung carcinoma, with stronger correlations observed in advanced tumor stages. Squamous cell carcinoma exhibited higher FDG uptake compared to adenocarcinoma. The integration of these biomarkers with histopathological and biochemical parameters can improve diagnostic accuracy and prognostication in lung cancer patients. Further studies are needed to explore the combined use of metabolic and systemic biomarkers to enhance treatment planning.