FDG PET as a prognostic predictor in the early post-therapeutic evaluation for unresectable hepatocellular carcinoma

To elucidate the prognostic role of post-therapeutic (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET), we conducted a retrospective cohort study analysing the clinical factors that affect overall survival after non-operative therapy for unresectable hepatocellular carcinoma (HCC). Sixty-seven cases with unresectable HCC who received non-operative therapy (transcatheter arterial chemoembolization: n = 24, transcatheter arterial infusion chemotherapy: n = 31, radiofrequency ablation: n = 5 or systemic chemotherapy: n = 7) and had received FDG PET for the evaluation of the therapeutic effect within 1 month after the end of the therapy were evaluated. Overall survival rate was evaluated using the univariate and multivariate analyses of relevant clinical and laboratory parameters before and after therapy, including visual PET analysis and quantitative analysis using maximum standardized uptake value (SUV). Visual PET diagnosis of post-therapeutic lesions was a good predictor of overall survival of unresectable HCC patients. The low FDG group showed significantly longer survival (average: 608 days) than that (average: 328 days) of the high FDG group (p < 0.0001). Multivariate analysis showed four significant prognostic factors for the survival: post-therapeutic alpha-fetoprotein (alpha FP) level (=400 ng/ml, p = 0.004), post-therapeutic visual PET diagnosis (p = 0.006), post-therapeutic clinical stage (UICC stage IV, p = 0.04) and post-therapeutic Milan criteria (p = 0.03), while pre-therapeutic clinical factors, SUV by post-therapeutic FDG PET (5.0 or more) or others did not show significance. The present study suggests that post-therapeutic PET performed within 1 month after non-operative therapy can be a good predictor of overall survival in unresectable HCC patients, while pre-therapeutic evaluation including PET, tumour markers and clinical staging may not be useful.