Abstract
BACKGROUND: Liver transplant (LT) is one of the main treatment options in selected patients with hepatocellular carcinoma (HCC). Overall, macrovascular invasion has been shown to be associated with an increased risk of tumor recurrence and mortality after LT in HCC. Macrovascular invasion detected on imaging is often considered a contraindication for LT in HCC. AIM: To investigate the effect of macrovascular invasion in explant on post-LT survival in HCC patients using a large national transplant database in the United States. METHODS: LT recipients with HCC between the years 2012 and 2022 were identified by using the United Network for Organ Sharing/Organ Procurement Transplant Network database. Patients who underwent deceased-donor LT with available liver explant pathology data were included. Kaplan-Meier curves were used for survival analysis, and multistep regression analysis was used to determine the predictors of mortality. RESULTS: A total of 13638 LT recipients with HCC and available explant pathology were included. Of these, 254 (1.8%) showed macrovascular invasion, 1712 (12.6%) had microvascular invasion, and 11672 (85.6%) had absent invasion. Poor tumor differentiation was more common with macrovascular invasion than with microvascular or absent invasion (22.4%, 17.7%, and 5.1%, respectively, P < 0.001). Post-transplant survival at 1 year, 3 years, and 5 years was lower in the macrovascular group than in the microvascular and absent invasion cohort (83.6%, 66.6%, 55.7% vs 90.8%, 76.2%, 66.6% vs 93.9%, 86.8%, 80.7%, P < 0.001). Similarly, transplant recipients whose explants were poorly differentiated had worse 1-year, 3-year, and 5-year survival than those with well-differentiated tumors and those with complete necrosis (86.1%, 67.1%, 60.4% vs 94.3%, 87.7%, 81.9% vs 94.8%, 89.7%, 84.2%, P < 0.001). In multivariable modeling, macrovascular invasion was associated with higher mortality risk compared to absent invasion [hazard ratio (HR) = 2.3, 95%CI: 1.9-2.7], and poor differentiation carried greater mortality risk than complete necrosis (HR = 2.3, 95%CI: 2.0-2.7). CONCLUSION: Macrovascular invasion accounted for a minority of cases at 1.8%. Macrovascular invasion and poor tumor differentiation on liver explants in patients with HCC were associated with significantly higher post-LT mortality, meaning that the extent of tumor involvement and tumor biology are important predictors of post-LT survival in HCC. However, the overall 5-year survival in patients with macrovascular invasion may still be within an acceptable range.