A novel classification of portal venous tumor invasion to predict residual tumor status after surgery in patients with pancreatic neuroendocrine neoplasms

To elucidate whether portal venous tumor invasion (PVTI) is a prognostic factor for patients with pancreatic neuroendocrine neoplasms (Pan-NENs). From 2002 to 2019, 240 patients with Pan-NEN were included to examine prognostic factors. PVTI based on computed tomography (CT) images are classified into four types: no PVTI (Vp0/1), PVTI not invading the superior mesenteric vein (Vp2), PVTI invading the superior mesenteric vein or portal vein (Vp3), and PVTI invading the portal bifurcation (Vp4). Simultaneous liver metastases (SLM) determined the overall survival (OS) in 240 patients. The 5-year OS rates with and without SLM were 46% and 92%, respectively (P