Systemic Therapy With or Without Upfront Transarterial Embolization for Inoperable Liver Metastasis of Neuroendocrine Tumors

Inclusion Criteria: * Diagnosis of NET of gastroenteropancreatic (GEP), pulmonary or unknown primary site origin * Unresectable liver metastases, according the judgment of surgeon, (the reasons for the opinion of surgeon should be made explicit) * Hepatic involvement ≤50% volume of the organ * Radiological evidence of hepatic lesions (contemporaneous progression or appearance of extrahepatic lesions are allowed if not critical sites) that require change or initiation of systemic pharmacotherapy * Patients undergoing , previously treated , or never treated with systemic medical therapy are eligible * Patients with or without carcinoid syndrome are eligible * Well (G1) or medium (G2) differentiated histology (according to WHO 2010 classification) * Ki67 ≤ 20% (G1-G2) * Life expectancy \> 6 months * Age ≥ 18 and \< 80 years Exclusion Criteria: * Previous loco-regional post-surgical treatment * Poorly differentiated histology * Severe concomitant morbidities such as: severe coagulopathy, severe liver failure (to be detailed), renal failure (creatinine \> 2.0 mg/dl) and heart failure (NYHA 3-4 or unstable ischemic heart disease), contraindicating the interventional procedure or influencing the general prognosis (Investigator to provide details of exclusion) * Extrahepatic metastasis in critical locations as: brain, spinal cord, lung with respiratory impairment, symptomatic vertebral lesions * Patients with only extra-hepatic lesions