This is a medical question of type : stages 
 What are the stages of Bile Duct Cancer (Cholangiocarcinoma) ? 
 Key Points
                    - The results of diagnostic and staging tests are used to find out if cancer cells have spread.    - There are three ways that cancer spreads in the body.    - Cancer may spread from where it began to other parts of the body.    - Stages are used to describe the different types of bile duct cancer.         - Intrahepatic bile duct cancer     - Perihilar bile duct cancer     - Distal extrahepatic bile duct cancer        - The following groups are used to plan treatment:         - Resectable (localized) bile duct cancer     - Unresectable, metastatic, or recurrent bile duct cancer
                
                
                    The results of diagnostic and staging tests are used to find out if cancer cells have spread.
                    The process used to find out if cancer has spread to other parts of the body is called staging. For bile duct cancer, the information gathered from tests and procedures is used to plan treatment, including whether the tumor can be removed by surgery.
                
                
                    There are three ways that cancer spreads in the body.
                    Cancer can spread through tissue, the lymph system, and the blood:         - Tissue. The cancer spreads from where it began by growing into nearby areas.     - Lymph system. The cancer spreads from where it began by getting into the lymph system. The cancer travels through the lymph vessels to other parts of the body.     - Blood. The cancer spreads from where it began by getting into the blood. The cancer travels through the blood vessels to other parts of the body.
                
                
                    Cancer may spread from where it began to other parts of the body.
                    When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumor) and travel through the lymph system or blood.         - Lymph system. The cancer gets into the lymph system, travels through the lymph vessels, and forms a tumor (metastatic tumor) in another part of the body.    - Blood. The cancer gets into the blood, travels through the blood vessels, and forms a tumor (metastatic tumor) in another part of the body.        The metastatic tumor is the same type of cancer as the primary tumor. For example, if bile duct cancer spreads to the liver, the cancer cells in the liver are actually bile duct cancer cells. The disease is metastatic bile duct cancer, not liver cancer.
                
                
                    Stages are used to describe the different types of bile duct cancer.
                    Intrahepatic bile duct cancer            -  Stage 0: Abnormal cells are found in the innermost layer of tissue lining the intrahepatic bile duct. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ.     -  Stage I: There is one tumor that has spread into the intrahepatic bile duct and it has not spread into any blood vessels.     -  Stage II: There is one tumor that has spread through the wall of the bile duct and into a blood vessel, or there are multiple tumors that may have spread into a blood vessel.      -  Stage III: The tumor has spread through the tissue that lines the abdominal wall or has spread to organs or tissues near the liver such as the duodenum, colon, and stomach.      -  Stage IV: Stage IV is divided into stage IVA and stage IVB.                  - Stage IVA: The cancer has spread along the outside of the intrahepatic bile ducts or the cancer has spread to nearby lymph nodes.       - Stage IVB: The cancer has spread to organs in other parts of the body.                         Perihilar bile duct cancer            -  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: Cancer has formed in the innermost layer of the wall of the perihilar bile duct and has spread into the muscle layer or fibrous tissue layer of the wall.     -  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 stage IIIA and stage IIIB.                  - Stage IIIA: Cancer has spread to branches on one side of the hepatic artery or of the portal vein.        - Stage IIIB: Cancer has spread to nearby lymph nodes. Cancer may have spread into the wall of the perihilar bile duct or through the wall to nearby fatty tissue, the liver, or to branches on one side of the hepatic artery or of the portal vein.                -  Stage IV: Stage IV is divided into stage IVA and stage IVB.                   - Stage IVA: Cancer has spread to one or more of the following:                           - the main part of the portal vein and/or common hepatic artery;          - the branches of the portal vein and/or common hepatic artery on both sides;           - 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.                  Cancer may have spread to nearby lymph nodes.       - Stage IVB: Cancer has spread to lymph nodes in more distant parts of the abdomen, or to organs in other parts of the body.                         Distal extrahepatic bile duct cancer            -  Stage 0: Abnormal cells are found in the innermost layer of tissue lining the distal extrahepatic bile duct. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ.     -  Stage I: Stage I is divided into stage IA and stage IB.                  - Stage IA: Cancer has formed and is found in the distal extrahepatic bile duct wall only.       - Stage IB: Cancer has formed and has spread through the wall of the distal extrahepatic bile duct but has not spread to nearby organs.                -  Stage II: Stage II is divided into stage IIA and stage IIB.                  - Stage IIA: Cancer has spread from the distal extrahepatic bile duct to the gallbladder, pancreas, duodenum, or other nearby organs.       - Stage IIB: Cancer has spread from the distal extrahepatic bile duct to nearby lymph nodes. Cancer may have spread through the wall of the duct or to nearby organs.                -  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:  Cancer has spread to organs in distant parts of the body.
                
                
                    The following groups are used to plan treatment:
                    Resectable (localized) bile duct cancer    The cancer is in an area, such as the lower part of the common bile duct or perihilar area, where it can be removed completely by surgery.       Unresectable, metastatic, or recurrent bile duct cancer     Unresectable cancer cannot be removed completely by surgery. Most patients with bile duct cancer cannot have their cancer completely removed by surgery.     Metastasis is the spread of cancer from the primary site (place where it started) to other places in the body. Metastatic bile duct cancer may have spread to the liver, other parts of the abdominal cavity, or to distant parts of the body.      Recurrent bile duct cancer is cancer that has recurred (come back) after it has been treated. The cancer may come back in the bile ducts, liver, or gallbladder. Less often, it may come back in distant parts of the body.