Liver Transplantation for Unresectable Neuroendocrine Tumor Liver Metastases

Liver transplantation (LT) is performed in selected patients with neuroendocrine hepatic metastases. Survival benefit and the risk of tumor recurrence after LT, also exacerbated by immunosuppressive therapy, remain important clinical issues. Whether patients with particular types of neuroendocrine tumors (NET) benefit more than others is unclear. Bibliographical searches were performed in PubMed for the terms "liver transplantation and neuroendocrine tumors," "liver transplant and neuroendocrine tumors," "liver transplantation and immunosuppressive therapy," "tumor recurrence." Promising results have been reported for LT for NET metastases with 5-year survival of up to 90 % in patients with well-differentiated gastroenteropancreatic NETs, but only few patients are free of tumor 5 years after LT. Better outcomes have been reported for gastrointestinal tumors than for pancreatic NETs for both survival and risk or recurrence after LT. Selection criteria for LT are limited and include the 2007 Milan Criteria and the 2012 European Neuroendocrine Tumor Society guidelines, including: well-differentiated NET (Ki-67 < 10 %), age < 55 years, absence of extrahepatic disease, primary tumor removed before transplantation, stable disease for at least 6 months before LT, and < 50 % liver involvement. LT might be considered in carefully selected patients. The risk of tumor recurrence remains a significant clinical problem after LT, but data focused on immunosuppression issue are lacking, and there are no currently approved strategies for prevention of recurrence or follow-up protocols. Further studies are needed to define universally accepted inclusion criteria, reliable predictors of better outcome, and optimal timing for LT.