Survival Insights in Locally Advanced Gallbladder Cancer: The Role of 18F-FDG PET/CT

Gallbladder carcinoma (GBC) is an aggressive malignancy with a poor prognosis, often diagnosed at a locally advanced stage. Accurate risk stratification is crucial for optimizing treatment, yet conventional imaging and staging systems have limitations. This study aimed to evaluate the prognostic value of metabolic and volumetric parameters from 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in patients with locally advanced GBC. This retrospective study included 32 patients with biopsy-confirmed, locally advanced GBC who underwent baseline 18F-FDG PET/CT. The standard uptake values (SUVmax, SUVmean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured for both primary tumors and nodal metastases. A univariate Cox proportional hazards model was used to assess the association between these volumetric metabolic PET parameters and progression-free survival (PFS) and overall survival (OS). The multivariate Cox model was used to test the independence of significant univariate prognostic factors. In the univariate analysis of volumetric metabolic PET parameters of primary tumors, higher pSUVmean (hazard ratio [HR]: 1.39, p = 0.04), pTLG2.5 (per 100 units; HR: 1.01, p = 0.02), pMTV40 (HR: 1.00, p = 0.02), and pTLG40 (per 100 units; HR: 1.09, p = 0.01) were all significantly associated with worse OS. Similar significant associations were found for PFS. Notably, the conventional metric of pSUVmax was not a significant predictor of either PFS (p = 0.11) or OS (p = 0.25). On multivariate analysis, pTLG40 remained an independent predictor of survival. Furthermore, none of the volumetric metabolic PET parameters derived from nodal metastases showed a significant association with survival outcomes. Volumetric metabolic PET parameters, particularly TLG and MTV, which reflect the total metabolic burden of the primary tumor, may offer greater prognostic utility in locally advanced GBC compared with the conventional SUVmax. These parameters should be considered for integration into prognostic models to enhance patient risk stratification and guide personalized therapeutic strategies.