Risk factors and classifications of hilar cholangiocarcinoma

Table 1 Memorial Sloan-Kettering Cancer Center classification

Stage	Criteria
T1	The tumor involves the biliary confluence with unilateral involvement up to secondary biliary radicles. There is no portal vein involvement or liver atrophy
T2	The tumor involves the biliary confluence with unilateral involvement up to secondary biliary radicles. There is ipsilateral portal vein involvement or ipsilateral hepatic lobar atrophy
T3	The tumor involves the biliary confluence with bilateral involvement up to secondary biliary radicles, unilateral extension to secondary biliary radicles with contralateral portal vein involvement, unilateral involvement up to secondary biliary radicles with contralateral hepatic lobar atrophy, or main/bilateral portal vein involvement

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.

Table 3 Consensus classification (European Hepato-Pancreato-Biliary Association)

Label	Side location	Description
Bile duct (B)
B1		Common bile duct
B2		Hepatic duct confluence
B3	R	Right hepatic duct
B3	L	Left hepatic duct
B4		Right and left hepatic duct
Tumor size (T)
T1		< 1 cm
T2		1-3 cm
T3		≥ 3 cm
Tumor form (F)
Sclerosing		Sclerosing (or periductal)
Mass		Mass-forming (or nodular)
Mixed		Sclerosing and mass-forming
Polypoid		Polypoid (or intraductal)
Involvement (> 180°) of the portal vein (PV)
PV0		No portal involvement
PV1		Main portal vein
PV2		Portal vein bifurcation
PV3	R	Right portal vein
PV3	L	Left portal vein
PV4		Right and left portal veins
Involvement (> 180°) of the hepatic artery (HA)
HA0		No portal involvement
HA1		Proper hepatic artery
HA2		Hepatic artery bifurcation
HA3	R	Right hepatic artery
HA3	L	Left hepatic artery
HA4		Right and left hepatic artery
Liver remnant volume (V)
V0		No information on the volume needed (liver resection not foreseen)
V%	Indicate segments	Percentage of the total volume of a putative rem-nant liver after resection
Underlying liver disease (D)		Fibrosis
		Nonalcoholic steatohepatitis
		Primary sclerosing cholangitis
Lymph nodes (N)
N0		No lymph node involvement
N1		Hilar and/or hepatic artery lymph node involvement
N2		Periaortic lymph node involvement
Metastases (M)
M0		No distant metastases
M1		Distant metastases (including liver and peritoneal metastases)

R: Right; L: Left.