18F-FDG PET/CT predicts survival after 90Y transarterial radioembolization in unresectable hepatocellular carcinoma.
PURPOSE
To compare the value of pretreatment functional and morphological imaging parameters for predicting survival in patients undergoing transarterial radioembolization using yttrium-90 (90Y-TARE) for unresectable hepatocellular carcinoma (uHCC).


METHODS
We analysed data from 48 patients in our prospective database undergoing 90Y-TARE treatment for uHCC (31 resin, 17 glass). All patients underwent 18F-FDG PET/CT and morphological imaging (CT and MRI scans) as part of a pretherapeutic work-up. Patients did not receive any treatment between these imaging procedures and 90Y-TARE. Kaplan-Meier estimates of progression-free survival (PFS) and overall survival (OS) were used to assess the prognostic value of 18F-FDG PET/CT metabolic parameters, including SUVmax, tumour-to-liver (T/L) uptake ratio and SUVmean of healthy liver, and morphological data, including number and size of lesions, portal-venous infiltration (PVI). Relevant prognostic factors for HCC including Child-Pugh class, Barcelona Clinic Liver Cancer (BCLC) stage, tumour size, PVI and serum AFP level were compared with metabolic parameters in univariate and multivariate analyses.


RESULTS
The median follow-up in living patients was 16.2 months (range 11.4-50.1 months). Relapse occurred in 34 patients (70.8%) at a median of 7.4 months (range 1.4-27.9 months) after 90Y-TARE, and relapse occurred in 24 of 34 patients (70.8%) who died from their disease at a median of 8.1 months (range 2.2-35.2 months). Significant prognostic markers for PFS were the mean and median lesion SUVmax (both P = 0.01; median PFS 10.2 vs. 7.4 months), and significant prognostic markers for OS were the first quarter (Q1) cut-off values for lesion SUVmax and T/L uptake ratio (both P = 0.02; median OS 30.9 vs. 9 months). The multivariate analysis confirmed that lesion SUVmax and T/L uptake ratio were independent negative predictors of PFS (hazard ratio, HR, 2.7, 95% CI 1.2-6.1, P = 0.02, for mean SUVmax; HR 2.6, 95% CI 1.1-5.9, P = 0.02, for median SUVmax:) and OS (HR 3.2, 95% CI 1-10.9, P = 0.04 for Q1 SUVmax; HR 3.7, 95% CI 1.1-12.2, P = 0.03, for Q1 T/L uptake ratio), respectively, when testing with either the BCLC staging system or serum AFP level.


CONCLUSION
Lesion SUVmax and T/L uptake ratio as assessed by 18F-FDG PET/CT, but not morphological imaging, were predictive markers of survival in patients undergoing 90Y-TARE for uHCC.