After extrahepatic bile duct cancer has been diagnosed, tests are done to find out if cancer cells have spread within the bile duct or to other parts of the body.

The process used to find out if cancer has spread within the extrahepatic bile duct or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment.

Extrahepatic bile duct cancer may be staged following a laparotomy. A surgical incision is made in the wall of the abdomen to check the inside of the abdomen for signs of disease and to remove tissue and fluid for examination under a microscope. The results of the diagnostic imaging tests, laparotomy, and biopsy are viewed together to determine the stage of the cancer. Sometimes, a laparoscopy will be done before the laparotomy to see if the cancer has spread. If the cancer has spread and cannot be removed by surgery, the surgeon may decide not to do a laparotomy.

There are three ways that cancer spreads in the body.

The three ways that cancer spreads in the body are:

• Through tissue. Cancer invades the surrounding normal tissue.
• Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
• Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.

When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.

There are two staging systems for extrahepatic bile duct cancer.

Extrahepatic bile duct cancer has two staging systems. The staging system used depends on where in the extrahepatic bile duct the cancer first formed.

• Perihilar or proximal extrahepatic bile duct tumors (perihilar bile duct tumors) form in the area where the bile duct leaves the liver. This type of tumor is also called a Klatskin tumor.
• Distal extrahepatic bile duct tumors (distal bile duct tumors) form in the area where the bile duct empties into the small intestine.

The following stages are used for perihilar extrahepatic bile duct cancer:

Stage 0 (Carcinoma in Situ)

In stage 0, abnormal cells are found in the innermost layer of tissue lining the perihilar bile duct. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ.

Stage I

In stage I, cancer has formed in the innermost layer of the wall of the perihilar bile duct and has spread into the muscle and fibrous tissue of the wall.

Stage II

In stage II, cancer has spread through the wall of the perihilar bile duct to nearby fatty tissue or to the liver.

Stage III

Stage III is divided into stages IIIA and IIIB.

• Stage IIIA: The tumor has spread to one branch of the hepatic artery or of the portal vein (vessels that carry blood to and from the liver).
• Stage IIIB: The tumor has spread to nearby lymph nodes. Cancer has also spread into the wall of the perihilar bile duct and may have spread through the wall to nearby fatty tissue, the liver, or to one branch of the hepatic artery or of the portal vein (vessels that carry blood to and from the liver).

Stage IV

Stage IV is divided into stages IVA and IVB.

• Stage IVA: The tumor may have spread to nearby lymph nodes and has spread to one or more of the following:
  • the main part of the portal vein (a vessel that carries blood away from the liver) or both branches of the portal vein;
  • the hepatic artery (a vessel that carries blood to the liver);
  • the right and left hepatic ducts;
  • the right hepatic duct and the left branch of the hepatic artery or of the portal vein;
  • the left hepatic duct and the right branch of the hepatic artery or of the portal vein.
• Stage IVB: The tumor has spread to other parts of the body, such as the liver.

The following stages are used for distal extrahepatic bile duct cancer:

Stage 0 (Carcinoma in Situ)

In stage 0, abnormal cells are found in the innermost layer of tissue lining the distal bile duct. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ.

Stage I

In stage I, cancer has formed. Stage I is divided into stages IA and IB.

• Stage IA: Cancer is found in the distal bile duct only.
• Stage IB: Cancer has spread all the way through the wall of the distal bile duct.

Stage II

Stage II is divided into stages IIA and IIB.

• Stage IIA: Cancer has spread from the distal bile duct to the gallbladder, pancreas, small intestine, or other nearby organs.
• Stage IIB: Cancer has spread from the distal bile duct to nearby lymph nodes. Cancer may have spread through the wall of the distal bile duct or to the gallbladder, pancreas, small intestine, or other nearby organs.

Stage III

In stage III, cancer has spread to the large vessels that carry blood to the organs in the abdomen. Cancer may have spread to nearby lymph nodes.

Stage IV

In stage IV, cancer has spread to other parts of the body, such as the liver or lungs.

Extrahepatic bile duct cancer can also be grouped according to how the cancer may be treated. There are two treatment groups:

Localized (and resectable)

The cancer is in an area where it can be removed completely by surgery.

Unresectable, recurrent, or metastatic

Unresectable cancer cannot be removed completely by surgery. Most patients with extrahepatic bile duct cancer have unresectable cancer.

Recurrent cancer is cancer that has recurred (come back) after it has been treated. Extrahepatic bile duct cancer may come back in the bile duct or in other parts of the body.

Metastasis is the spread of cancer from the primary site (place where it started) to other places in the body. Metastatic extrahepatic bile duct cancer may have spread to nearby blood vessels, the liver, the common bile duct, nearby lymph nodes, other parts of the abdominal cavity, or to distant parts of the body.