Clinical and radiological response to locoregional and systemic treatments in well-differentiated gastroenteropancreatic neuroendocrine tumors with liver metastases treated at a reference center in Mexico.

644 Background: liver metastases (LM) from well-differentiated gastroenteropancreatic neuroendocrine tumors (wd-GEP-NET) can develop in 28-77% of patients (pts) in their lifetime. Multiple treatments can provide radiological and symptomatic response. Our aim was to evaluate responses to locoregional (LRT) and systemic (SYST) treatments in wd-GEP-NET with LM. Methods: we included consecutive records of pts with confirmed histological diagnosis of wd-GEP-NET and radiological LM, treated at our institution between 2008-2019. Relevant variables were retrospectively extracted from electronic records. Radiological response was assessed with RECIST 1.1 by radiological independent review. Results: 55 pts, 45.5% male. Median age at LM diagnosis 49 years (IQR 41-63). Primary tumor sites: 49% pancreatic, 27.3% small intestine, 11% unknown, 12.7% others. WHO 2019 grade 1, 2 and 3 in 52.7, 41.8 and 1.8%, respectively. Twentynine tumors (52.7%) were functional, with carcinoid syndrome in n20. At LM diagnosis, 91% of pts had symptomatic disease: hormonal n8, local n4, systemic n4, hormonal + local n4, local + systemic n22, hormonal + systemic n5, hormonal + local + systemic n5. LM tumoral burden was <10% in 22%, 11-50% in 43.6, > 50% in 30.9% of pts. 49.1% of pts had extra hepatic metastatic disease. LRT to LM was administered to 32 pts: TAE/TACE n26, ablation n8. SYST to 22 pts: somatostatin analog n15, Lutetium-177 n4, chemotherapy n2, everolimus n1. 1 pt did not receive treatment. Response to treatments is shown. In the LRT group, -- pts developed complications: n16 postembolization syndrome, n2 infections, n3 liver failure, n7 others. There was 1-procedure-related death. Conclusions: Patients treated with LRT at our institution achieved similar efficacy and safety results compared to those reported by previous studies.[Table: see text]