Staging is the process of finding out how far a cancer has spread. The stage (extent) of bile duct cancer is one of the most important factors in selecting treatment options and estimating a patient's outlook for recovery and survival (prognosis).

A staging system is a standardized way for members of the cancer care team to summarize the extent of a cancer's spread. The stage of a cancer can be determined by the results of the physical exam, imaging tests (ultrasound, CT or MRI scan, etc.) and other tests, which are described in the section, "How is bile duct cancer diagnosed?" and by the results of surgery if it has been done.

The American Joint Committee on Cancer (AJCC) TNM system

The major system used to describe the stages of bile duct cancer is the American Joint Committee on Cancer (AJCC) TNM system. There are actually 2 different staging systems for bile duct cancers, depending on where they start.

Intrahepatic bile duct cancers (those starting within the liver) are staged the same way as other cancers that start in the liver. The TNM staging system for liver cancers is described in detail in our document, Liver Cancer.

Extrahepatic bile duct cancers (those starting outside of the liver) make up the majority of bile duct cancers and have their own staging system. The TNM system for extrahepatic bile duct cancers contains 3 key pieces of information:

• T describes whether the main tumor has invaded through the wall of the bile duct and whether it has invaded other nearby organs or tissues.

• N describes whether the cancer spread to nearby (regional) lymph nodes (bean-sized collections of immune system cells located throughout the body).

• M indicates whether the cancer has metastasized (spread) to other organs of the body. (The most common sites of bile duct cancer spread are the liver, peritoneum [the lining of the abdominal cavity], and the lungs.)

Numbers or letters appear after T, N, and M to provide more details about each of these factors:

• The numbers 0 through 4 indicate increasing severity.
• The letter X means "cannot be assessed" because the information is not available.

T categories for extrahepatic bile duct cancer

TX: No description of the tumor's extent is possible because of incomplete information.

T0: There is no evidence of a primary tumor.

Tis (carcinoma in situ): Cancer cells are limited to the mucosa (the innermost layer of the bile duct) and have not invaded deeper layers of the bile duct. This stage is also known as intramucosal carcinoma.

T1: The cancer has invaded deeper but is still confined to the bile duct.

T2: The cancer has grown through the bile duct wall but has not reached nearby structures.

T3: The cancer invades nearby structures such as the liver, gallbladder, pancreas, or a branch of one of the large blood vessels leading into the liver (portal vein or hepatic artery).

T4: The cancer invades into the main portal vein (or both main branches), the common hepatic artery, or other structures such as the duodenum (first part of the small intestine), colon, stomach, or abdominal wall.

N categories for extrahepatic bile duct cancer

M categories for extrahepatic bile duct cancer

Stage grouping

Once a patient's T, N, and M categories have been determined, this information is combined in a process called stage grouping. The stage is expressed in Roman numerals from stage 0 (the least advanced stage) to stage IV (the most advanced stage). Some stages are subdivided with letters.

Stage 0 (Tis, N0, M0): The cancer is confined to the innermost layer of the bile duct and has not spread to lymph nodes or distant sites.

Stage IA (T1, N0, M0): The cancer has invaded deeper but is still confined to the bile duct. It has not spread to lymph nodes or distant sites.

Stage IB (T2, N0, M0): The cancer has grown through the bile duct but has not invaded nearby organs or structures and has not spread to nearby lymph nodes or distant sites.

Stage IIA (T3, N0, M0): The cancer invades nearby structures such as the liver, gallbladder, pancreas, or branches of the portal vein or hepatic artery. It has not spread to nearby lymph nodes or distant sites.

Stage IIB (T1, 2, or 3; N1; M0): The cancer may or may not have spread outside of the bile duct to nearby organs. It has spread into nearby lymph nodes but not to distant sites.

Stage III (T4, N0 or 1, M0): The cancer invades into the main portal vein, the common hepatic artery, duodenum (first part of the small intestine), colon, stomach, or abdominal wall. It may or may not have spread to nearby lymph nodes but has not spread to distant sites.

Stage IV (Any T, any N, M1): The cancer has spread to distant sites.

Resectable versus unresectable cancers

The TNM system divides bile duct cancers into several groups that help give doctors an idea about a person's prognosis (outlook). But for treatment purposes, doctors often use a simpler system based on whether these cancers are likely to be resectable (completely removable by surgery) or unresectable. In general terms, most stage III and IV tumors are unresectable, but there may be exceptions. Resectability is based not only on the extent of the tumor, but also on where it is located along the bile duct and whether or not a person is healthy enough to have surgery.

Survival statistics for bile duct cancers

Survival rates are a way for doctors to discuss and compare the prognosis (outlook) for patients, based on the stage of the cancer or other traits. Accurate survival rates can be hard to determine for bile duct cancers because these cancers are not common. Some of the more important factors affecting survival include the location and extent of the cancer, whether or not it is resectable, and a person's general health.

There are some important points to note about the survival rates below:

• The 5-year survival rate refers to the percentage of patients who live at least 5 years after being diagnosed. Of course, some of these patients live much longer than 5 years after diagnosis.

• These numbers are among the most current we have available, but they represent people who were first diagnosed and treated several years ago. Because of improvements in treatment since then (including more aggressive surgery), survival rates for people now being diagnosed with these cancers may be higher.

• While survival statistics can sometimes be useful as a general guide, they may not accurately represent any one person's prognosis. A number of other factors, including other tumor characteristics, how the cancer was treated, and a person's age and general health, can also affect outlook. Your doctor is likely to be a good source as to whether these numbers may apply to you, as he or she is familiar with the aspects of your particular situation.

Resectable bile duct cancers

Intrahepatic bile duct cancers: These cancers start within the liver. Probably about half of these cancers are resectable at the time they are found. For intrahepatic bile duct cancers that are removable by surgery, 5-year survival rates have been reported to be between 20% and 40%.

Hilar bile duct cancers: These cancers begin in the area where the branches of the bile duct have just left the liver. Only a small portion of these cancers are resectable when they are first found. Even in these cases, the operation is often extensive and complex. Studies have found 5-year survival rates for these cancers ranging from about 10% to 30%.

Distal bile duct cancers: These cancers have started further down the bile duct. They are more likely to be resectable than hilar bile duct cancers, but in many cases the operation requires removal of part of the pancreas and small intestine. The 5-year survival rates reported in studies range from about 15% to about 40%.

Unresectable bile duct cancers

Unfortunately, bile duct cancers that cannot be removed by surgery can be hard to treat effectively. Most studies have reported 5-year survival rates of less than 10% for these cancers. This rate is significantly higher in people with intrahepatic or hilar bile duct cancers who are treated with a liver transplant.