Staging Distal Cholangiocarcinoma
Distal cholangiocarcinomas are found further down the bile duct, closer to the small intestine and pancreas. Because these bile ducts are outside of the liver, these cancers are grouped with perihilar cancers as extrahepatic cholangiocarcinoma. Distal cholangiocarcinomas make up 2 to 3 of every 10 bile duct cancers.
After a person is diagnosed with distal bile duct cancer, doctors will try to figure out if it has spread, and if so, how far. This process is called staging. The stage of a cancer describes how much cancer is in the body. It helps determine how serious the cancer is and how best to treat it. Doctors also use a cancer's stage when talking about survival statistics.
The earliest stage distal bile duct cancers are stage 0, also called carcinoma in situ (CIS) or high-grade biliary intraepithelial neoplasia. Stages then range from stages I (1) through IV (4). As a rule, the lower the number, the less the cancer has spread. A higher number, such as stage IV, means cancer has spread more. And within a stage, an earlier letter means a lower stage.
Although each person’s cancer experience is unique, cancers with similar stages tend to have a similar outlook and are often treated in much the same way.
How is the stage determined?
The staging system most often used for distal bile duct cancer is the American Joint Committee on Cancer (AJCC) TNM system, which is based on 3 key pieces of information:
- The extent (size) of the main tumor (T): Has the cancer grown through the wall of the bile duct? Has the cancer reached nearby structures or organs?
- The spread to nearby lymph nodes (N): Has the cancer spread to nearby lymph nodes?
- The spread (metastasis) to distant sites (M): Has the cancer spread to distant lymph nodes or distant organs such as the bones, lungs, or peritoneum (the lining of the abdomen [belly])?
The system described below is the most recent AJCC system, effective January 2018.
Numbers or letters after T, N, and M provide more details about each of these factors. Higher numbers mean the cancer is more advanced.
Once a person’s T, N, and M categories have been determined, this information is combined in a process called stage grouping to assign an overall stage. For more on this, see Cancer Staging.
Distal bile duct cancer is typically given a clinical stage based on the results of a physical exam, biopsy, and imaging tests (described in Tests for Bile Duct Cancer). If surgery is done, the pathologic stage (also called the surgical stage) is determined by examining the tissue removed during the operation.
Cancer staging can be complex, so ask your doctor to explain it to you in a way you understand.
Click to enlarge. Tumor sizes are often measured in centimeters (cm) or inches. Common food items that can be used to show tumor size in cm include: a pea (1 cm), a peanut (2 cm), a grape (3 cm), a walnut (4 cm), a lime (5 cm or 2 inches), an egg (6 cm), a peach (7 cm), and a grapefruit (10 cm or 4 inches).
Click to enlarge. Millimeters (mm). A sharp pencil point is about 1 mm, a new crayon point is about 2 mm, and a new pencil eraser is about 5 mm.
Click to enlarge and play video. Many cancer deaths are caused when cancer moves from the original tumor and spreads to other tissues and organs. This is called metastatic cancer. This animation shows how cancer cells travel from the place in the body where they first formed to other parts of the body.
T Categories for Distal Bile Duct Cancer
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.
(Tis, N0, M0)
The cancer cells are only growing in the mucosa (the innermost layer of the bile duct) (Tis) and have not grown into deeper layers of the bile ducts or any nearby organs or structures. It has not spread to lymph nodes (N0) or distant sites (M0).