Table 3.

TNM staging

Staging	0	I	II	IIIA	IIIB	IIIC	IVA	IVB
T	TIS	1	2a-b	3	4	random	random	random
N	0	0	0	0	0	1	2	random
M	0	0	0	0	0	0	0	1

Note:

Tumor size (T);

TX: The primary tumor cannot be evaluated; T0: No evidence of primary tumor; Tis: Carcinoma in situ/Severe dysplasia; T1: Limited to bile ducts, reaching muscularis or fibrous tissue; T2a: Beyond the bile duct wall to the surrounding adipose tissue; T2b: Invasion of adjacent liver parenchyma; T3: Invasion of one branch of the portal vein or hepatic artery; T4: Invasion of the portal vein or its bilateral branches, or common hepatic artery, or bilateral secondary bile ducts; or tumor invasion of one secondary bile duct into the contralateral portal vein or hepatic artery.

Regional lymph nodes (N);

NX: Regional lymph node metastasis cannot be determined; N0: No regional lymph node metastasis; N1: 1 to 3 regional lymph nodes metastases; N2: Metastases in ≥4 regional lymph nodes;

Distant metastasis (M);

M0: No distant metastasis; M1: Distant metastases (including lymph node metastases beyond the hepatoduodenal ligament and the area behind the pancreatic head and duodenum).