Prognostic and predictive value of metabolic tumor volume on ¹⁸F-FDG PET/CT in advanced biliary tract cancer treated with gemcitabine/oxaliplatin with or without erlotinib

This study aimed to evaluate the prognostic significance and predictive performance of volume-based parameter of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) in biliary tract cancer (BTC). Of the 268 patients who were enrolled onto phase III gemcitabine/oxaliplatin (GEMOX) versus GEMOX/erlotinib trial, a total of 48 patients had pretreatment ¹⁸F-FDG PET/CT available for analysis. Maximum standardized uptake value (SUV_max), metabolic tumor volume (MTV), and total lesion glycolysis for the primary tumor were measured. The prognostic significance of these parameters and clinicopathological variables was assessed by Cox proportional hazards regression analysis. A cutoff of 98.8 ml for the MTV_liver was the best discriminative value for predicting overall survival (>9 months). Multivariate analyses with adjustments for age, performance status, and disease status showed that only MTV_liver was an independent prognostic factor associated with overall survival (HR 2.149, 95 % CI 1.124–4.109, P = 0.021). SUV_max did not show any correlation with overall survival. For patients in the high-MTV_MBP group, overall survival was longer in the chemotherapy plus erlotinib group than in the chemotherapy-alone group [median 8.3 months (5.5–11.1) vs. 4.0 months (0.0–8.0); P = 0.048]. MTV may be considered as a significant independent metabolic prognostic factor for overall survival in patients with BTC and predictive marker for the selection of patients for the addition of erlotinib to first-line chemotherapy.