Diagnostic-therapeutic management of bile duct cancer

Table 2 Eighth edition of the TNM classification of the AJCC/UICC (2017-2018)[30] - Perihilar cholangiocarcinoma

Primary tumor (pT)	Regional lymph nodes (pN)	Distant metastasis (pM)	Stage grouping
TX: Primary tumor cannot be assessed	NX: Regional lymph nodes cannot be assessed		Stage 0: Tis N0 M0; Stage I: T1 N0 M0; Stage II: T2a-b N0 M0; Stage IIIA: T3 N0 M0; Stage IIIB: T4 N0 M0; Stage IIIC: any T N1 M0; Stage IVA: any T N2 M0; Stage IVB: any T any N M1
T0: No evidence of primary tumor	N0: No regional lymph node metastasis	M0: No distant metastasis
Tis: Carcinoma in situ/high grade dysplasia
T1: Tumor confined to the bile duct, with extension up to the muscle layer or fibrous tissue	N1: One to three positive lymph nodes typically involving the hilar, cystic duct, common bile duct (choledochal), hepatic artery, posterior pancreatoduodenal and portal vein lymph nodes	M1: Distant metástasis
T2: Tumor invades beyond the wall of the bile duct to surrounding adipose tissue or tumor invades adjacent hepatic parenchyma; T2a: Tumor invades beyond the wall of the bile duct to surrounding adipose tissue; T2b: Tumor invades adjacent hepatic parenchyma	N2: Four or more positive lymph nodes from the sites described for N1
T3: Tumor invades unilateral branches of the portal vein or hepatic artery
T4: Tumor invades the main portal vein or its branches bilaterally or the common hepatic artery; or unilateral second order biliary radicles with contralateral portal vein or hepatic artery involvement