Metabolic grading of HCC in the palliative BCLC C stage: Strong prediction of survival by FDG PET

Objectives This study aims to evaluate the role of metabolic grading with 18 F-FDG PET/CT for prognostification of patients with advanced hepatocellular carcinoma (HCC) of Barcelona Clinic Liver Cancer classification C (BCLC C).

Methods In a dual-center evaluation, we retrospectively assessed the outcome of 96 patients with advanced HCC (BCLC C) undergoing 18F-FDG PET/CT within the staging work-up. Tumors with the highest SUVmax were selected as target lesions. In order to normalize tumor SUV values the ratio of SUVmax of the tumor lesion to SUVmean of normal liver parenchyma, the tumor-to-liver ratio (T/L Ratio), was calculated. Patients were divided into three metabolic grading groups (mG): mG1 (T/L SUV Ratio <2), mG2 (T/L SUV Ratio 2-5) and mG3 (T/L SUV Ratio >5). Survival analyses were performed using the Kaplan-Meier method (log-rank test) for univariate and the cox-proportional hazards model for multivariate analyses, p< 0.05 was considered statistically significant.

Results The mean follow-up period was 18 months. The median overall survival (OS) of the entire cohort was 11 mo (95% CI, 8-14). 42 patients (43.8 %) were in the mG1 group, 44 patients (45.8 %) in mG2 group and 10 patients (10.4 %) in mG3 group. Metabolic grading had a significant impact on OS and patients with mG1 had a significantly longer OS than the remaining (mG2+mG3) patients (31 mo, 95% CI 6-57 vs. 8 mo, 95% CI 5-12; p=0.007). Distinction of mG2 versus mG3 tumors was also significant with longer OS of patients in mG2 group (median 10 mo, 95% CI 6-14) than patients in mG3 group (median 3 mo, 95% CI 1-9; p=0.048).

Conclusions Metabolic grading with FDG PET may serve as a powerful prognostic tool for patients with advanced HCC (BCLC C) by predicting survival and significantly complementing the BCLC staging system.