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

## TL;DR

This study shows that [18F]FDG PET/CT imaging can help identify patients with aggressive liver cancer before transplantation, improving risk assessment and outcomes.

## Contribution

The study demonstrates that [18F]FDG PET/CT can predict microvascular invasion and early cancer recurrence in liver transplant patients.

## Key findings

- PET/CT positivity was independently associated with microvascular invasion in explanted livers.
- Patients with PET/CT-positive tumors had a higher risk of early cancer recurrence after transplantation.
- Incorporating PET/CT into selection criteria may improve patient stratification and post-transplant outcomes.

## Abstract

Liver transplantation can cure hepatocellular carcinoma (HCC), but some patients still experience cancer recurrence after surgery, especially within the first two years. Accurately identifying patients at higher risk of recurrence before transplantation remains challenging, as standard selection criteria mainly rely on tumor size and number and do not fully reflect tumor aggressiveness. In this study, we evaluated whether a metabolic imaging technique, [18F]FDG PET/CT, could help improve risk assessment before liver transplantation. We analyzed a Western cohort of patients who underwent liver transplantation for HCC and compared PET/CT findings with detailed pathological features of the explanted liver and post-transplant outcomes. We found that tumors showing increased glucose uptake on PET/CT were more likely to display microvascular invasion, a pathological feature strongly associated with early cancer recurrence after transplantation. Importantly, PET/CT positivity indirectly identified patients at higher risk of early recurrence by identifying aggressive tumor biology before surgery. These findings suggest that [18F]FDG PET/CT may provide valuable additional information beyond conventional imaging and could help refine patient selection and post-transplant surveillance strategies in liver transplantation for HCC.

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.