AIMTo evaluate circulating endothelial lineage cells (ELCs) as biomarkers of tumor neovascularization in patients with pancreatic ductal adenocarcinoma (PDAC).MATERIALS AND METHODSELCs were isolated from the peripheral blood of patients with PDAC (n=14) or controls (n=17) before and after tumor resection/surgery and quantified using flow cytometry. Vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) were detected in tumor using immunohistochemistry and in plasma using an ELISA technique.RESULTSCirculating ELC levels were increased in patients with PDAC compared to controls. After PDAC resection, ELC levels declined. ELC level increases were associated with cancer recurrence. VEGF and PlGF were identified in cancer cells and exocrine pancreas cells. Only PlGF was detected in tumor-associated inflammatory cells. Plasma levels of PlGF were higher in patients with PDAC compared to controls.CONCLUSIONCirculating ELCs are a potential biomarker of PDAC neovascularization, and PlGF may be an important target in treatment of PDAC.