Stage is the word doctors use to communicate the size of a cancerous tumor and where and how far it has spread. The first place cancer is found in the body is called the primary site or primary tumor. When a cancer spreads to distant parts of the body, it is said to have metastasized. There are two types of stages of cancer, clinical and pathological.
The clinical stage helps your doctor decide on the best treatment options for you. For bile duct cancer, your clinical stage is determined from biopsies and imaging tests.
The pathological stage is determined based on examination of your bile duct after it is removed by surgery. Sometimes the pathological stage is higher because the tumor has spread more than was expected during clinical staging.
By using exams and tests, a doctor can tell the stage of the bile duct cancer. A cancer's stage is one of the most important factors in deciding what treatment to have for the cancer. Both the International Union Against Cancer and the American Joint Committee on Cancer have developed a standard way to find out how much a cancer has grown. This system is known as the TNM system.
The TNM system is a standard system for describing the extent of a cancer's growth. Here's what the letters stand for in the TNM system:
T refers to where the tumor is (inside or through the bile duct) and whether it has spread outside of the bile duct into nearby areas such as the pancreas or a vein in the liver.
N refers to whether the lymph nodes in the area of the original tumor are cancerous.
M refers to whether the cancer has spread to other organs in the body (metastasized), such as the lungs or bones.
Once your T, N, and M stages have been determined, your doctor puts them together in a stage grouping. This is used to determine your overall cancer stage. Stage grouping is shown in Roman numerals going from 0 (the earliest stage) to IV (the most advanced stage). The following are the stage groupings used for extrahepatic bile duct cancer--the most common type of bile duct cancer, which occurs in the part of the bile duct outside the liver.
Stage 0. The cancer is only in the innermost layer of the bile duct. It has not spread to lymph nodes or distant sites in the body. This is also called carcinoma in situ.
Stage IA. The cancer is in the bile duct wall, but has not grown all the way through it. It has not spread to lymph nodes or distant sites in the body.
Stage IB. The cancer has grown through the bile duct wall but has not spread anywhere else.
Stage IIA. The cancer invades nearby structures, such as the liver, pancreas, or gallbladder. Or it may have spread to smaller branches of the hepatic artery or portal vein, but not into the larger vessels. It has not spread to lymph nodes or distant sites.
Stage IIB. The cancer is in the bile duct and has spread into lymph nodes but not to distant sites. It may or may not have spread to nearby structures.
Stage III. The cancer invades the main vein or arteries or part of the small intestine, gallbladder, colon, or stomach. It may or may not have spread to lymph nodes but has not spread to distant sites.
Stage IV. The cancer has spread to distant sites, such as the bones or lungs.
Your doctor considers the stage and your health to recommend a treatment plan. Staging information helps doctors compare your individual situation with other people who have had bile duct cancer. Based on clinical studies done on people in similar stages of the disease, a doctor can make some predictions about how the cancer may act and how different treatments may work.