Risk factors and classifications of hilar cholangiocarcinoma

Table 2 Perihilar bile duct tumors (American Joint Commission on Cancer Staging 7^th edition)

T1	Tumor confined to bile duct histologically
T2a	Tumor beyond the wall of bile duct into adjacent fat
T2b	Tumor beyond the wall of bile duct into liver parenchyma
T3	Tumor invades ipsilateral portal vein (R or L) or hepatic artery (R or L)
T4	Tumor invades
	(1) Main portal vein or its branches bilaterally (or)
	(2) Common hepatic artery (or)
	(3) The second-order biliary radicals bilaterally
	(4) Unilateral second-order biliary radicals with contralateral portal vein or hepatic artery involvement
Node
Nx	Regional lymph nodes cannot be assessed.
N0	No regional lymph node metastasis
N1	Regional lymph node metastasis (including nodes along the cystic duct, common bile duct, hepatic artery, and portal vein)
N2	Metastasis to periaortic, pericaval, superior mesenteric artery, and/or celiac artery lymph nodes
Metastasis
M0	No distant metastasis
M1	Distant metastasis
Tumor stage AJCC staging 6th edition
0	Tis, N0, M0
I	T1, N0, M0
II	T2a-b, N0, M0
IIIa	T3, N0, M0
IIIb	T1 or T2
	T3, N1, M0
IVa	T4, N0
	N1, M0
IVb	Any T, N2, M0
	Any T, any N, M1

AJCC: American Joint Committee on Cancer; R: Right; L: Left.