Prognostic significance of volume based metabolic parameters by 18F FDG PET/CT in gallbladder carcinoma

We investigated the prognostic values of volume based metabolic parameters by 18F fluorodeoxyglucose (18F FDG)positron emission tomography (PET)/computed tomography (CT)in gallbladder carcinoma patients and compared them with other prognostic parameters. We enrolled 44 patients, who were initially diagnosed with gallbladder carcinoma and under going 18F FDG PET/CT. Various metabolic volume based PET parameters of primary tumors, including maximum and average standardized uptake values (SUVmax, SUVavg), metabolic tumor volume (MTV), and total lesion glycolysis (TLG), were measured in gallbladder carcinoma patients using mediastinal blood pool activity as a threshold SUV for determining the tumor boundaries. Overall survival analysis was performed using the Kaplan Meier method with PET parameters and other clinical variables. For determining independent prognostic factors, Cox proportional hazards regression analysis was performed. Of the 44 enrolled patients, cancer- or treatment related death occurred in 30 (68.2%). The mean clinical follow up period was 22.2±10.4m (range, 0.6-35.9m). Univariate analysis demonstrated that clinical or pathologic TNM stage (P<0.001), treatment modality (P<0.001), MTV (cutoff=135cm3, P=0.001), and TLG (cutoff=7.090, P<0.05)were significant prognostic factors. In multivariate analysis, both clinical or pathologic TNM stage [hazard ratio (HR)=2.019 (I vs II), 21.287 (I vs III), and 24.354 (I vs IV); P=0.001)and TLG (HR=2.930; P<0.05)were independent prognostic factors for predicting overall survival. In gallbladder cancer, TLG of the primary tumor, a volume based metabolic parameter, is a significant independent prognostic factor for overall survival in conjunction with the clinical or pathological TNM stage