Staging of Intrahepatic Bile Duct Cancers

After a person is diagnosed with intrahepatic 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 intrahepatic bile duct cancers are stage 0 (also called carcinoma in situ, or CIS). 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 intrahepatic 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): How large has the cancer grown? Has the cancer 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 intrahepatic bile duct cancers (those starting within the liver). Staging systems for cancers starting in other parts of the bile ducts are described in:

• Perihilar Bile Duct Cancer Stages (for cancers starting in the hilum, just outside 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.

Intrahepatic 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 intrahepatic 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).
IA	T1a N0 M0	The tumor is no more than 5 cm (about 2 inches) across and has not invaded nearby blood vessels (T1a). It has not spread to nearby lymph nodes (N0) or to distant sites (M0).
IB	T1b N0 M0	The tumor is more than 5 cm (about 2 inches) across but has not invaded nearby blood vessels (T1b). The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).
II	T2 N0 M0	The tumor has grown into nearby blood vessels, OR there are 2 or more tumors, which may or may not have grown into nearby blood vessels (T2). The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).
IIIA	T3 N0 M0	The cancer has grown through the visceral peritoneum (the outer lining of organs in the abdomen) (T3). The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).
IIIB	T4 N0 M0	The cancer has grown directly into nearby structures outside of the liver (T4). The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).
	OR
	Any T N1 M0	The cancer is any size and might or might not be growing outside the bile duct (Any T) and has spread to nearby lymph nodes (N1). It has not spread to distant sites (M0).
IV	Any T Any N M1	The cancer is any size and may or may not be growing outside the bile duct (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 or lungs (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.