Portal vein tumor thrombus is a bottleneck in the treatment of hepatocellular carcinoma.

The effect of portal vein tumor thrombus (PVTT) on the prognosis of patients with hepatocellular carcinoma has become clear over the past several decades. However, identifying the mechanisms and performing the diagnosis and treatment of PVTT remain challenging. Therefore, this study aimed to summarize the progress in these areas. A computerized literature search in Medline and EMBASE was performed with the following combinations of search terms: "hepatocellular carcinoma" AND "portal vein tumor thrombus." Although several signal transduction or molecular pathways related to PVTT have been identified, the exact mechanisms of PVTT are still largely unknown. Many biomarkers have been reported to detect microvascular invasion, but none have proved to be clinically useful because of their low accuracy rates. Sorafenib is the only recommended therapeutic strategy in Western countries. However, more treatment options are recommended in Eastern countries, including surgery, radiotherapy (RT), transhepatic arterial chemoembolization (TACE), transarterial radioembolization (TARE), and sorafenib. Therefore, we established a staging system based on the extent of portal vein invasion. Our staging system effectively predicts the long-term survival of PVTT patients. Currently, several clinical trials had shown that surgery is effective and safe in some PVTT patients. RT, TARE, and TACE can also be performed safely in patients with good liver function. However, only a few comparative clinical trials had compared the effectiveness of these treatments. Therefore, more randomized controlled trials examining the extent of PVTT should be conducted in the future.