AIM:To investigate the expression level of plasma vascularendothelial growth factor(P-VEGF)in patients withhepatocellular carcinoma(HCC)and its relationship withthe clinicopathologic characteristics,and to examine thechanges of P-VEGF in the course of transcatheter arterialchemoembolization(TACE).METHODS:Peripheral blood samples were taken from 45HCC patients before and 1,3,7 d,and 1 mo after TACE.Plasma VEGF level was measured with the quantitativesandwich enzyme-linked immunosorbent assay(ELISA).Twenty patients with benign liver lesions and 17 healthycontrol subjects were also included in this study.RESULTS:Plasma VEGF levels in HCC patients weresignificantly elevated as compared to those in patients withbenign liver lesions(P=0.006)and in the normal controls(P=0.003).Significant differences were observed whenP-VEGF was categorized by tumor size(P=0.006),portalvein thrombosis(P=0.011),distant metastasis(P=0.017),arterial-portal vein shunting(P=0.026),and InternationalUnion Against Cancer(UICC)TNM stage(P=0.044).Therewas no correlation between plasma level of VEGF and thelevel of alpha fetoprotein(α-FP) (r=0.068,P=0.658)andweakly correlated with the number of platelets(r=0.312,P=0.038).P-VEGF levels increased significantly andreached the peak value on the first day after TACE,and thendecreased gradually.The change rate of P-VEGF concentration(one month post-TACE/pre-TACEx100%)was correlatedwith the retention rate of lipiodol oil(rs=0.494,P=0.001)and the tumor volume change(rs=0.340,P=0.034).The patients who achieved a partial or complete responseto TACE therapy showed significantly less pre-treatmentP-VEGF than those nonresponders(P=0.025).A high pre-therapeutic P-VEGF level was associated with poor responseto treatment(P=0.018).CONCLUSION:A high pre-treatment P-VEGF level is auseful marker for tumor progression,especially for vascular invasion.TACE increases the level of P-VEGF onlytemporarily which may be associated with tumor ischemia.P-VEGF may be useful in predicting treatment response,monitoring disease course after TACE and judging the effectof different TACE regimens.