| T: primary tumor | |
| TX | Primary tumor cannot be assessed |
| T0 | No evidence of primary tumor |
| Tis | Carcinoma in situ |
| T1 | Tumor invades bile duct wall to a depth less than 5 mm |
| T2 | Tumor invades bile duct wall to a depth of 5 mm up to 12 mm |
| T3 | Tumor invades bile duct wall to a depth of more than 12 mm |
| T4 | Tumor involves the celiac axis, the superior mesenteric artery or the common hepatic artery |
| N: regional lymph nodes | |
| NX | Regional lymph nodes cannot be assessed |
| N0 | No regional lymph node metastasis |
| N1 | Metastasis in 1?3 regional lymph nodes |
| N2 | Metastasis in 4 or more regional lymph nodes |
| M: distant metastasis | |
| M0 | No distant metastasis |
| M1 | Distant metastasis |
