Staging of Perihilar Bile Duct Cancers

After a person is diagnosed with perihilar (hilar) bile duct cancer, doctors will try to figure out if it has spread, and if so, how far. This process is called staging. The stage of a cancer describes how much cancer is in the body. It helps determine how serious the cancer is and how best to treat it. Doctors also use a cancer's stage when talking about survival statistics.

The earliest stage perihilar bile duct cancers are stage 0, also called carcinoma in situ (CIS) or high-grade biliary intraepithelial neoplasia. Stages then range from stages I (1) through IV (4). As a rule, the lower the number, the less the cancer has spread. A higher number, such as stage IV, means cancer has spread more. And within a stage, an earlier letter means a lower stage.

Although each person’s cancer experience is unique, cancers with similar stages tend to have a similar outlook and are often treated in much the same way.

How is the stage determined?

The staging system most often used for perihilar bile duct cancer is the American Joint Committee on Cancer (AJCC) TNM system, which is based on 3 key pieces of information:

• The extent (size) of the main tumor (T): Has the cancer grown through the bile duct or reached nearby structures or organs?
• The spread to nearby lymph nodes (N): Has the cancer spread to nearby lymph nodes?
• The spread (metastasis) to distant sites (M): Has the cancer spread to distant lymph nodes or distant organs such as the bones, lungs, or peritoneum (the lining of the abdomen [belly])?

The system described below is the most recent AJCC system, effective January 2018. It's used only for perihilar bile duct cancers (those starting in the hilum, just outside the liver). Staging systems for cancers starting in other parts of the bile ducts are described in: 

• Intrahepatic Bile Duct Cancer Stages (for cancers starting in bile ducts within the liver)
• Distal Bile Duct Cancer Stages (for cancers starting farther down the bile duct)

Numbers or letters after T, N, and M provide more details about each of these factors. Higher numbers mean the cancer is more advanced.

Once a person’s T, N, and M categories have been determined, this information is combined in a process called stage grouping to assign an overall stage. For more on this, see Cancer Staging.

Perihilar bile duct cancer is typically given a clinical stage based on the results of a physical exam, biopsy, and imaging tests (described in Tests for Bile Duct Cancer). If surgery is done, the pathologic stage (also called the surgical stage) is determined by examining the tissue removed during the operation. 

Cancer staging can be complex, so ask your doctor to explain it to you in a way you understand.

 Stages of perihilar bile duct cancer

AJCC Stage	Stage grouping	Stage description*
0	Tis N0 M0	The cancer is only in the mucosa (the innermost layer of cells in the bile duct). It hasn't started growing into the deeper layers (Tis). It has not spread to nearby lymph nodes (N0) or to distant sites (M0).
I	T1 N0 M0	The cancer has grown into deeper layers of the bile duct wall, such as the muscle layer or fibrous tissue layer (T1). It has not spread to nearby lymph nodes (N0) or to distant sites (M0).
II	T2a or T2b N0 M0	The tumor has grown through the bile duct wall and into the nearby fatty tissue (T2a) or into the nearby liver tissue (T2b). The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).
IIIA	T3 N0 M0	The cancer is growing into branches of the main blood vessels of the liver (the portal vein and/or the hepatic artery) on one side (left or right) (T3). The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).
IIIB	T4 N0 M0	The cancer is growing into the main blood vessels of the liver (the portal vein and/or the common hepatic artery) or into branches of these vessels on both sides (left and right), OR the cancer is growing into other bile ducts on one side (left or right) and a main blood vessel on the other side (T4). The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).
IIIC	Any T N1 M0	The cancer is any size and may or may not be growing outside the bile duct or into nearby blood vessels (Any T) and has spread to 1 to 3 nearby lymph nodes (N1). It has not spread to distant sites (M0).
IVA	Any T N2 M0	The cancer is any size and may or may not be growing outside the bile duct or into nearby blood vessels (Any T). It has also spread to 4 or more nearby lymph nodes (N2). It has not spread to distant sites (M0).
IVB	Any T Any N M1	The cancer is any size and may or may not be growing outside the bile duct or into nearby blood vessels (Any T). It may or may not have spread to nearby lymph nodes (Any N). It has spread to distant organs such as the bones, lungs, or distant parts of the liver (M1).

*The T categories are described in the table above, except for: 

• TX: Main tumor cannot be assessed due to lack of information.

• T0: No sign of a primary tumor. 

The N categories are described in the table above, except for: 

• NX: Nearby lymph nodes cannot be assessed due to lack of information.