Definition

Bile duct cancer, or cholangiocarcinoma, is a malignant
tumor of the bile ducts within the liver (intrahepatic),
or leading from the liver to the small intestine (extrahepatic).
It is a rare tumor with poor outcome for most patients.

Description

Bile is a substance manufactured by the liver that
aids in the digestion of food. Bile ducts are channels that
carry the bile from the liver to the small intestine. Like
the tributaries of a river, the small bile ducts in the liver
converge into two large bile ducts called the left and right
hepatic ducts. These exit the liver and join to form the
common hepatic duct. The gallbladder, which concentrates
and stores the bile, empties into the common
hepatic duct to form the common bile duct. Finally, this
large duct connects to the small intestine where the bile
can help digest food. Collectively, this network of bile
ducts is called the biliary tract.

Bile duct cancer originates from the cells that line
the inner surface of the bile ducts. A tumor may arise
anywhere along the biliary tract, either within or outside
of the liver. Bile duct tumors are typically slow-growing
tumors that spread by local invasion of neighboring
structures and by way of lymphatic channels.

Bile duct cancer is an uncommon malignancy. In the
United States, approximately one case arises per 100,000
people per year, but it is more common in Southeast
Asia. It occurs in men only slightly more often than in
women, and it is most commonly diagnosed in people in
their 50s and 60s.

Causes and symptoms

A number of risk factors are associated with the
development of bile duct cancer:

• Primary sclerosing cholangitis. This disease is characterized
by extensive scarring of the biliary tract, sometimes
associated with inflammatory bowel disease.
• Choledochal cysts. These are abnormal dilatations of
the biliary tract that usually form during fetal development.
There is evidence that these cysts may rarely
arise during adulthood.
• Hepatolithiasis. This is the condition of stone formation
within the liver (not including gallbladder stones).
• Liver flukes. Parasitic infection with certain worms is
thought to be at least partially responsible for the higher
prevalence of bile duct cancer in Southeast Asia.
• Thorotrast. This is a chemical that was previously
injected intravenously during certain types of x rays. It
is not in use anymore. Exposure to Thorotrast has been
implicated in the development of cancer of the liver as
well as the bile ducts.

Symptoms

Jaundice is the first symptom in 90% of patients.
This occurs when the bile duct tumor causes an obstruction
in the normal flow of bile from the liver to the small
intestine. Bilirubin, a component of bile, builds up within
the liver and is absorbed into the bloodstream in excess
amounts. This can be detected in a blood test, but it can
also manifest as yellowish discoloring of the skin and
eyes. The bilirubin in the bloodstream also makes the
urine appear dark. Additionally, the patient may experience
generalized itching due to the deposition of bile
components in the skin. Normally, a portion of the bile is
excreted in stool; bile actually gives stool its brown
color. But when the biliary tract is obstructed by tumor,
the stools may appear pale.

Abdominal pain, fatigue, weight loss, and poor
appetite are less common symptoms. Occasionally, if
obstruction of the biliary tract causes the gallbladder to
swell enormously yet without causing pain, the physician
may be able to feel the gallbladder during a physical
examination. Sometimes the biliary tract can become
infected, but this is normally a rare consequence of invasive
tests. Infection causes fever, chills, and pain in the
right upper portion of the abdomen.

Diagnosis

Certain laboratory tests of the blood may aid in the
diagnosis. The most important one is the test for elevated
bilirubin levels in the bloodstream. Levels of alkaline
phosphatase and CA 19-9 may also be elevated.

When symptoms, physical signs, and blood tests
poinmt toward an abnormality of the biliary tract, then
the next step involves radiographic tests. Ultrasound and
computed tomography (CT scan) are noninvasive and
rapid. These tests can often detect the actual tumor as
well as dilatation of the obstructed biliary tract. If these
tests indicate the presence of a tumor, then cholangiography
is required. This procedure involves injecting dye
into the biliary tract to obtain anatomic images of the bile
ducts and the tumor. The specialist that performs this test
can also insert small tubes, or stents, into a partially
obstructed portion of the bile duct to prevent further
obstruction by growth of the tumor. This is vitally important
since it may be the only intervention that is possible
in certain patients. Cholangiography is an invasive test
that carries a small risk of infection of the biliary tract.
The objective of these radiological tests is to determine
the size and location of the tumor, as well as the extent of
spread to nearby structures.

The treatment of bile duct tumors is usually not
affected by the specific type of cancer cells that comprise
the tumor. For this reason, some physicians forego biopsy
of the tumor.

Treatment

The treatment is with surgical resection (removal) of
the tumor and all involved structures. Unfortunately,
sometimes the cancer has already spread too far when the
diagnosis is made. Thus, in the treatment of bile duct cancer,
the first question to answer is if the tumor may be
safely resected by surgery with reasonable benefit to the
patient. If the cancer involves certain blood vessels or has
spread widely throughout the liver, then resection may not
be possible. Sometimes further invasive testing is required.
Angiography can determine if the blood vessels are
involved. Laparoscopy is a surgical procedure that allows
the surgeon to directly assess the tumor and nearby lymph
nodes without making a large incision in the abdomen. Only
about 45% of bile duct cancers are ultimately resectable.

ough to tolerate the operation, then the specific type of
surgery performed depends on the location of the tumor.
For tumors within the liver or high up in the biliary tract,
resection of part of the liver may be required. Tumors in
the middle portion of the biliary tract can be removed
alone. Tumors of the lower end of the biliary tract may
require extensive resection of part of the pancreas, small
intestine, and stomach to ensure complete resection.
Unfortunately, sometimes the cancer appears
resectable by all the radiological and invasive tests, but is
found to be unresectable during surgery. In this scenario, a
bypass operation can relieve the biliary tract obstruction,
but does not remove the tumor itself. This does not produce
a cure but it can offer a better quality of life for the patient.
Chemotherapy and radiation therapy have not
been proven effective in the treatment of bile duct cancer.

Prognosis

Prognosis depends on the stage and resectability of
the tumor. If the patient cannot undergo surgical resection,
then the survival rate is commonly less than one
year. If the tumor is resected, the survival rate improves,
with 20% of these patients surviving past five years.