Neuroendocrine Tumors Presenting with Liver Metastasis, is It Necessary to Find the Primary Site for a Better Outcome?

BACKGROUND/AIMS: Neuroendocrine tumors (NET) presenting with multiple liver metastasis are a heterogeneous group of tumors and their prognosis differs greatly from each other according to their differentiation, grade, and possibly to their primary site of origin. MATERIALS AND METHODS: Seven patients diagnosed with NET who presented with multiple liver metastases between October 2014 and November 2018 were included in this retrospective study. The patients' details, their tumor characteristics, the local and systemic treatments administered, the response evaluation and their survival data were collected from the hospital files and analyzed.RESULTS: The median age of the 7 patients was 50 (range: 27-64) years. Carcinoid syndrome was present in two patients. The histopathology of all the patients were consistent with well-differentiated NET. As an initial treatment, one patient underwent right hepatectomy. All patients received somatostatin analog for a median of 20.7 months (range: 6-48 months) as an initial systemic treatment. One patient received radionuclide therapy and palliative radiotherapy for bone metastasis, one patient received trans arterial chemo embolization to the liver and one patient received capecitabine and temozolamide treatment after progression to somatostatin analog treatment. The median progression free survival and median overall survival (follow-up) was 15 months (range: 6-48 months) and 17 months (range: 8-48 months) respectively. All patients were still alive at the end of this study. CONCLUSION: Primary unknown well-differentiated NETs presenting with liver metastasis have different clinical and survival characteristics than primary known metastatic NETs. Treating these patients as the same disease may not be appropriate.