Transarterial liver-directed therapies of neuroendocrine hepatic metastases

Neuroendocrine tumors (NETs) comprise a diverse group of slowly growing tumors with an indolent course, characterized by the capacity to synthesize and secrete polypeptide products that are hormonally active. Presence of liver metastases results in significant debilitating hormonal symptoms, and is associated with poor prognosis. Systemic chemotherapy has limited success in the management of patients with NET hepatic metastases. Although somatostatin analogs are effective in controlling symptoms in many of these patients, the disease can become refractory to treatment. For these reasons, interventional radiologic techniques for liver-directed therapy have become an important treatment option in patients with metastatic NETs. Transcatheter arterial procedures such as transarterial embolization (TAE), transarterial chemoembolization (TACE), and selective internal radiation therapy (SIRT) have been shown to reduce hormone levels, palliate symptoms, and reduce the tumor burden in many patients with unresectable and symptomatic NET hepatic metastases. This article summarizes the most recent information on arterial-based liver-directed therapies in the treatment of metastatic NETs.