Primary tumor (T)

• TX: Primary tumor cannot be assessed
• T0: No evidence of primary tumor
• Tis: Carcinoma in situ
• T1: Tumor confined to the bile duct histologically
• T2: Tumor invades beyond the wall of the bile duct
• T3: Tumor invades the liver, gallbladder, pancreas, and/or unilateral branches of the portal vein (right or left) or hepatic artery (right or left)
• T4: Tumor invades any of the following: main portal vein or its branches bilaterally, common hepatic artery, or other adjacent structures, such as the colon, stomach, duodenum, or abdominal wall

Regional lymph nodes (N)

• NX: Regional lymph nodes cannot be assessed
• N0: No regional lymph node metastasis
• N1: Regional lymph node metastasis

Distant metastasis (M)

• MX: Distant metastasis cannot be assessed
• M0: No distant metastasis
• M1: Distant metastasis

Stage 0

• Tis, N0, M0

Stage IA

• T1, N0, M0

Stage IB

• T2, N0, M0

Stage IIA

• T3, N0, M0

Stage IIB

• T1, N1, M0
• T2, N1, M0
• T3, N1, M0

Stage III

• T4, any N, M0

Stage IV

• Any T, any N, M1