The Predictive Role of [18F]FDG PET/CT in Early HCC Recurrence After Liver Transplantation

Background and aims: Liver transplantation is effective against hepatocellular carcinoma (HCC), but recurrence remains a challenge. Traditional criteria based on tumor size, nodule number, and AFP levels have had limited success in predicting aggressiveness. [18F]FDG PET/CT has shown promise in identifying high-risk tumor features, including microvascular invasion (MVI), which is a key predictor of recurrence. Methods: In this retrospective, single-center study, all consecutive patients who underwent LT for HCC between 2010 and 2019 were included. Prior to listing, the patients underwent [18F]FDG PET/CT, and explant pathology was analyzed for MVI and other histological features. The primary objective was to identify the predictors of early HCC recurrence (within 24 months after LT). Secondary objectives included identifying predictors of high-risk histological features of the explant, describing recurrence patterns, and assessing post-recurrence survival. Results: The study included 143 patients (median age 59 years [IQR 54-64], 85% males, median MELD 10 [IQR 8-14], median AFP value 8.5 [IQR 4-39] ng/mL) and 40 (28%) with intra-hepatic [18F]FDG PET/CT positivity. HCC recurred post-LT in 25 patients (17%) (median post-LT follow-up 49 months [IQR 28.5-77]) and within 24 months in 12 patients (48%). MVI at the explant stage was independently associated with early recurrence (HR: 7.20, 95% CI 1.82-28.45, p = 0.005), while intra-hepatic [18F]FDG PET/CT positivity before LT independently predicted MVI in explants (OR 3.90, 95% CI 1.30-11.71, p = 0.01). Conclusions: [18F]FDG PET/CT may offer a valuable tool for pre-transplant risk assessment by identifying MVI, which is an independent predictor of early cancer recurrence. Its incorporation into the selection criteria for LT may enhance patient stratification and post-transplant outcomes.