Microvascular Venous Invasion in Hepatocellular Carcinoma: Why Do Recurrences Occur?

Hepatocellular carcinoma is the most common primary cancer of the liver. It is almost always associated with cirrhosis and it is usually diagnosed in later stages of the disease. Furthermore, recurrence rate following liver transplantation ranges between 15 and 30%. The most important factor determining the recurrence is vascular invasion. In this review, the issue of microvascular invasion causing hepatocellular carcinoma recurrence is reviewed. Macroscopic vascular invasion is almost easy to diagnose on radiologic evaluation. However, microscopic vascular invasion is almost always diagnosed with pathologic evaluation. On the other hand, microscopic vascular invasion is associated with early recurrences and reduced disease-free survival. The type of vessel that is invaded determines the nature of the spread of the tumor cells. Invasion of the hepatic venous tributaries leads to systemic metastasis whereas portal venous invasions lead to intrahepatic spread of the tumor. Microscopic vascular invasion should be diagnosed before liver transplantation or liver resection in order to deliver the appropriate therapy to the patients. Yet, there is no ideal marker to suggest microscopic vascular invasion before any intervention. Markers such as alpha-fetoprotein, des carboxy prothrombin, or gamma-glutamyl transferase have been found to be correlated with microscopic vascular invasion. These parameters are not very efficient to be used in routine clinical practice. Therefore, further research is needed to define ideal marker associated with microscopic vascular invasion.