Bile duct cancer, or cholangiocarcinoma, is a type of liver cancer that begins in the cells of the bile duct, a thin, tubelike structure that delivers bile from your liver to your small intestines. Bile is a greenish liquid produced by your liver cells that helps your body digest fats from the food you eat. The five-inch-long bile duct system begins as tiny ductules that are located throughout the liver. These ductules collect bile and merge to form larger ducts outside of the liver, and these join the cystic duct from the gall bladder. This final merger forms the common bile duct. The common bile duct travels through the pancreas and releases bile from the liver and gallbladder into the duodenum, the first section of the small intestine.
Scientists do not know exactly what causes bile duct cancer. It is believed to be the result of mutations in the DNA of bile duct cells. These mutations are not inherited.
There are three types of bile duct cancer. They are grouped according to location. The three types of bile duct cancer are:
Perihilar (Hilar) Bile Duct Cancer
Also known as Klatskin tumors, perihilar or hilar cancer arises where the bile ducts merge and exit the liver. This is the most common type of bile duct cancer.
Distal Bile Duct Cancer
Distal bile duct cancer occurs in the last part of the bile duct system, which passes through your pancreas and ends in your duodenum. Because it occurs in the area that is outside of your liver, this is also called extrahepatic bile duct cancer.
Intrahepatic Bile Duct Cancer
This bile duct cancer arises in the part of the bile duct system that is inside the liver. According to The American Cancer Society (ACS), about one in 10 bile duct cancers are intrahepatic. (ACS, 2012)
Bile duct cancer is uncommon. However, certain factors and conditions may put you at greater risk for developing this type of cancer.
Long-standing inflammation is a key risk factor for developing bile duct cancer. Conditions that are associated with this kind of inflammation include:
- sclerosing cholangitis, which causes inflammation, scarring, and sometimes destruction of the bile ducts
- ulcerative colitis, which causes ulcers in the rectum lining and colon
- bile duct stones
- cirrhosis, which is progressive scarring of the liver that is most often caused by caused by alcohol abuse and infections such as hepatitis C and B
Nearly 60 percent of people who develop bile duct cancer are over the age of 65.
Liver Fluke Infection
Flukes are parasitic worms that can enter your body if you eat undercooked freshwater fish that contains parasites. The liver flukes live in the bile ducts. The species of fluke connected to bile duct cancer is mostly found in Southeast Asia.
Other Risk Factors
Most cases of bile duct cancer go undetected until the cancer has grown enough to cause symptoms. Growth of bile duct cancer obstructs the flow of bile from the liver to the small intestine, causing jaundice, or yellowing of the eyes and skin. Jaundice is the most common symptom of bile duct cancer. Other symptoms may include:
- weight loss
- abdominal pain
- decreased appetite
- fatigue and weakness
- clay-colored stools
Your doctor will diagnosis bile duct cancer by reviewing your medical history, asking questions about your symptoms, and doing a physical examination. They may also order one or more of the following tests to confirm a diagnosis of bile duct cancer:
Liver Function Tests
These blood tests (especially alkaline phosphatase and bilirubin) show how well the liver is functioning.
Abdominal CT Scan
A computed tomography (CT) scan is a specialized X-ray diagnostic test that tells doctors what the liver and other organs look like. It can show bile duct blockage and tumor locations.
A CT scanner can be used to help doctors obtain a small sample of tissue from a tumor. The tissue is examined under a microscope and identified. The identity, or type, of the tumor will guide treatment.
Endoscopic Retrograde Cholangiopancreatography (ERCP)
Staging Bile Duct Cancer
If your doctor determines that cancer is present, the next step is to determine the stage, or extent, of the cancer. Knowing how far the cancer has spread will help determine the best course of treatment. Staging will depend on where the cancer starts; for example, bile duct cancers that start within the liver are staged differently than those that begin outside of the liver. However, the American Joint Comittee on Cancer uses a TNM system to classify all types of bile duct cancers:
- T describes the extent of the tumor and whether it has invaded nearby organs or tissues
- N describes whether the cancer has spread to nearby lymph cells (small collections of immune cells that are distributed throughout the body)
- M describes whether or not the cancer has metastasized, or spread, to other organs
Treatment for bile duct cancer depends on the type and severity of the cancer. Surgery is often used to remove tumors and relieve bile flow obstruction. Bile duct cancer that is caught early may only require minimally invasive surgery to remove part of the bile duct. More advanced cases may require the removal of nearby tissues and lymph nodes. The type of surgery depends on the type of bile duct cancer. For example:
- Bile duct cancer inside the liver requires parts of the liver to be removed. Sometimes the entire liver has to be removed and replaced with a transplant.
- Bile duct cancer located outside of the liver in the lower part of the bile duct system can be treated with a Whipple surgical procedure. This involves removing the gallbladder and parts of the pancreas, bile duct, and small intestine. The surgeon then reconnects the remaining organs.
Chemotherapy and radiation are sometimes used after surgery to destroy or shrink tumors and prevent the spread of cancer, but it is not known how effective this is. According to the Mayo Clinic, these treatments are often used in addtion to surgery or a transplant. (Mayo Clinic)
Long-term outlook for bile duct cancer depends on a variety of factors, including your age and overall health, type and severity of the cancer, and how quickly it was treated. Survival rates depend on whether all of the cancer can be removed.
The National Center for Biotechnology Information (NCBI) states that approximately 40 percent of patients whose cancer is completely removed live five years or more. If tumors cannot be completely removed, full recovery is generally not possible. With continued medication and treatment, 50 percent of patients live for a least a year after diagnosis, with the other 50 percent living longer than one year. (NCBI, 2012)