The American Cancer Society describes the bile duct as a tube that extends from the liver to the small intestine, and helps transport bile to the small intestine to help break down fats in food. Cancer that starts in this tube is called bile duct cancer. The National Cancer Institute groups intrahepatic bile duct cancer, or cancer that starts in bile ducts in the liver, with liver cancer. Extrahepatic bile duct cancer is cancer that originates in bile ducts that are not in the liver. The American Cancer Society estimates that 9 out of 10 bile duct cancers are extrahepatic. After this cancer is diagnosed, it is then staged, which involves using a standardized system of classifying the spread and extent of the cancer. Staging also helps guide treatment and prognosis.
Stage 0 (Carcinoma in Situ)
The first stage of bile duct cancer is Stage 0, or carcinoma in situ, which is noninvasive cancer. In this stage, according to the American Cancer Society, the cancer is only in the innermost layer of the bile duct, called the mucosa. It is not in any lymph nodes or other organs.
Stage I
Stage I bile duct cancer involves one tumor that has started to invade into more layers of the wall of the bile duct like the muscle layer, but has not reached any blood vessels. There is no cancer in any lymph nodes or distant organs.
Stage II
The National Cancer Institute separates Stage II bile duct cancer into Stage IIA and IIB. Stage IIA bile duct cancer is when the cancer has invaded the liver, gallbladder, pancreas and/or either side of the hepatic artery or portal vein. Stage IIB involves cancer that has spread to adjacent lymph nodes, as well as either the bile duct, the bile duct wall, or the liver, gallbladder, pancreas, or either side of the hepatic artery or portal vein.
Stage III
Stage III bile duct cancer is split into two sub-stages, Stage IIIA and IIIB. Stage IIIA is diagnosed when the cancer has started to invade the main blood vessels on one side of the liver, like the portal vein or the hepatic artery, according to the American Cancer Society. Lymph nodes and other organs are cancer free. Stage IIIB cancer encompasses cancer that has invaded the deeper layers of tissue in the duct wall, and possibly grown through the wall into surrounding fat or liver tissue. Cancer may be in the main blood vessels of the liver on one side. Nearby lymph nodes may have cancer in them, but distant organs are not cancerous. According to the National Cancer Institute, Stage III bile duct cancer may also include cancer that has spread to nearby organs like the colon, stomach, small intestine or abdominal wall.
Stage IV
The American Cancer Society splits Stage IV, the last stage of bile duct cancer, into two sub-stages as well: Stage IVA and IVB. In Stage IVA, the cancer is invading the main blood vessels of the liver, or the branches of these veins on both sides of the liver, or the cancer is also invading other bile ducts, while the tumor also reaches at least one of the main blood vessels. Adjacent lymph nodes might be cancerous, but distant organs are cancer free. Stage IVB is diagnosed when lymph nodes distant to the tumor are cancerous, or the cancer has spread to distant organs like the lungs or bones.
