Table 1. PVTT classification system from the Liver Cancer Study Group of Japan25,26.

Grade	Definition
Vp0	Absence of invasion of (or tumor thrombus in) the portal vein
Vp1	Invasion of (or tumor thrombus in) distal to the second-order branches of the portal vein, but not of the second-order branches
Vp2	Invasion of (or tumor thrombus in) second-order branches of the portal vein
Vp3	Invasion of (or tumor thrombus in) first-order branches of the portal vein
Vp4	Invasion of (or tumor thrombus in) the main trunk of the portal vein and/or contra-lateral portal vein branch to the primarily involved lobe

PVTT, portal vein tumor thrombus.