Neuroendocrine tumours (NET) are a clinically challenging and heterogeneous collection of neoplasms that may arise from multiple primary sites comprising the diffuse neuroendocrine cell system, but most commonly do so from the gastrointestinal tract, pancreas and lungs [1]. Recent epidemiological evidence demonstrates a 6-fold increase in incidence since the 1990s [2], [3], [4], and institutional experience of high rates of metastatic disease at initial diagnosis has contradicted historical perceptions of these tumours are rare, indolent entities. The high rate of metastasis to locoregional lymph nodes and the liver present notable clinical considerations – between 67-91% of small intestinal NET and 28-77% of pancreatic NET treated at specialist centres display evidence of hepatic metastases [5], [6], and such disease spread exerts a substantial, negative prognostic effect [4].

Three categories of neuroendocrine hepatic metastases have been defined, based on lesion size and morphologic distribution through the liver [7]. Type I disease refers to the presence of single metastatic deposit of any size; type II refers to isolated metastatic bulk accompanied by smaller deposits (usually in both liver lobes); type III manifests as disseminated metastatic spread throughout the hepatic parenchyma [7]. The distribution of neuroendocrine metastases in the liver in combination with tumour grade and patient status can inform treatment strategies [1], [7], [8].

Therapy for neuroendocrine liver metastases (NELM) may involve several components of a broad armamentarium comprising surgery, somatostatin analogues, peptide receptor radionuclide therapy, cytotoxic chemotherapy, molecularly targeted agents, or liver-directed strategies [9]. Surgical approaches such as hepatectomy with microscopically clear margins (R0) or liver transplantation are the only strategies that possess curative intent for patients with NELM (combined with extirpation of locoregional disease) [10], [11], [12]. However, only a minority of patients are suitable for these approaches due to technical and oncological resectability. For hepatectomy, recurrence after resection may be high [10], and for transplantation, there is considerable debate around patient selection [12]. Somatostatin analogues [13], PRRT [14] and the molecularly targeted agents sunitinib [15] and everolimus [16], [17] were shown to exert anti-proliferative effects in randomised trials of patients with advanced, metastatic NET which manifested as prolonged progression-free survival. However, this has not been translated into a significant impact on overall survival.

Another set of techniques of increasing interest in the treatment of non-resectable NELM is ‘liver directed’ approaches [18] – these are percutaneous direct ablation and angiographic, interventional radiological procedures which seek to exploit principles of the pathological vascular anatomy of hepatic metastases to deliver targeted therapy.

This review article summarises the current evidence regarding outcomes from surgical approaches for the treatment of NELM, the principles underpinning liver-directed therapy for NELM, and the methods and key results obtained with different forms thereof. This review focuses on recent developments and outlines future perspectives in this developing field.