18F-FDG PET independently predicts survival in patients with HCC treated with 90Y microsphere radioembolization

Objectives FDG-PET/CT is of prognostic value in patients with liver metastases undergoing radioembolization with 90Y microspheres (RE). However, for HCC the predictive role of PET has not yet been investigated in this setting. The aim was to evaluate pre- and post-therapeutic FDG PET/ CT for predicting survival in patients with unresectable HCC undergoing RE.

Methods We retrospectively analyzed a consecutive cohort of n=34 patients with non-resectable HCC undergoing RE (mean activity 1.8 GBq) with FDG-PET/CT pre- and 1 month post-treatment. According to the baseline FDG metabolic status of the HCC lesions, patients were divided into 2 groups: FDG-negative (n=14) and FDG-positive (n=20) patients. FDG-positive patients were separated to early metabolic responders and non-responders according to the post-treatment relative change of SUVmax in the treated lesions and of the tumor-to-liver ratio (T/L-R). Overall survival was analyzed with the Kaplan-Meier method (log-rank test, p<0.05).

Results The median overall survival (OS) after radioembolization was 13 months (95% CI, 11-15). FDG-negative patients had a significantly longer OS (19 mo, 95% CI 5-33) than FDG-positive patients (9 mo, 95% CI 6-11; p<0.001). Among FDG positive patients, metabolic responders survived significantly longer than non-responders (p=0.043). Out of the other baseline variables, only the tumor burden had a significant impact on overall survival in the univariate analysis (p=0.008). In the multivariate analysis, however, tumoral FDG status at baseline and post-treatment was the only independent predictor of survival (hazard ratio, 3.3 (95%CI 1.6-6.5); p< 0.001).

Conclusions Pre- and post-therapeutic FDG-PET independently predicts overall survival in patients with HCC undergoing radioembolization. The assessment of early metabolic response 1 month post-treatment allows significant risk stratification and may impact individualized treatment strategies.