Predictors of Long-Term Outcomes After Liver Transplantation for Unresectable Metastatic Neuroendocrine Tumors

BACKGROUND: Malignant and benign neuroendocrine tumors (NET) share many histopathological features. Liver transplantation (LT) is one of the liver-directed therapies for neuroendocrine liver metastases (NELM). The aim of this study was to determine the outcomes of patients undergoing LT for NELM. MATERIAL/METHODS: This was a retrospective study that included 19 patients who underwent LT for unresectable NELM between December 1989 and December 2022 in the Department of General, Transplant, and Liver Surgery of the Medical University of Warsaw. Kaplan-Meier estimator and Cox proportional hazards regression were used for statistical analyses. RESULTS: The primary tumor was located most frequently in the pancreas. The median follow-up was 72.5 months. The overall survival (OS) was 94.7%, 88.0%, 88.0%, 70.4%, and 49.3% after 1, 3, 5, 10, and 15 years, respectively. Accordingly, the recurrence-free survival (RFS) rates were 93.8%, 72.9%, 64.8%, 27.8%, and 27.8% after 1, 3, 5, 10, and 15 years, respectively. Ki-67 index ≥5% was found as a risk factor for both worse OS (hazard ratio (HR) 7.13, 95% confidence intervals (95% CI) 1.32–38.63, P=0.023) and RFS (HR 13.68, 95% CI 1.54–121.52, P=0.019). Recipient age ≥55 years was a risk factor for worse RFS (P=0.046, HR 5.47, 95% CI 1.03–29.08). Multivariable analysis revealed Ki-67 ≥5% as the sole independent factor for worse OS (HR 13.78, 95% CI 1.48–128.56, P=0.021). CONCLUSIONS: Patients with unresectable NELM achieve great OS and satisfying RFS after LT. The risk factors associated with worse outcomes are attributed to primary tumor aggressiveness.