Epidemiology
Cholangiocarcinoma, also known as bile duct cancer, is a relatively uncommon disease. In the United States, approximately 8,000 people are diagnosed with this cancer each year, making it a rare condition compared to other cancers[2]. The disease typically affects older adults, with most patients receiving their diagnosis around the age of 70. Some sources note that the disease commonly occurs in people older than 50, though it can develop at any age[1][2].
Globally, the incidence and death rates from cholangiocarcinoma have been increasing in recent years. The disease is more prevalent in certain parts of the world, particularly in Southeast Asia, where it is linked to chronic infections with a liver fluke parasite called clonorchiasis, which is associated with the Chinese liver fluke[2][13]. This geographic variation highlights how environmental and infectious factors can influence the occurrence of the disease.
Causes
The exact cause of cholangiocarcinoma remains unclear to medical experts. However, the disease is believed to develop when abnormal changes occur in the DNA (the material inside cells that contains instructions for how cells behave) of the cells lining the bile ducts. These DNA changes can cause the cells to grow and divide without stopping, eventually forming tumors that damage surrounding tissues[2][13].
One specific type of gene change that can lead to cholangiocarcinoma is called a fibroblast growth factor receptor 2 (FGFR2) fusion. This occurs when parts of two different genes abnormally join together. The resulting abnormal protein can become overactive, causing bile duct cells to grow and divide uncontrollably, leading to tumor growth. FGFR2 fusion is one of the most common gene changes found in people with intrahepatic cholangiocarcinoma (the type that forms inside the liver)[8].
Health conditions that cause chronic, long-term inflammation in the bile ducts are believed to play a role in the development of this cancer. Ongoing damage from inflammation can trigger the DNA changes that lead to tumor formation[2][13].
Risk Factors
Certain health conditions and lifestyle factors can increase the likelihood of developing cholangiocarcinoma. Primary sclerosing cholangitis, a progressive disease in which the bile ducts become blocked by inflammation and scarring, is a notable risk factor. People with chronic ulcerative colitis, a form of inflammatory bowel disease, also face increased risk[7].
Other conditions that raise the risk include cysts in the bile ducts, which block the flow of bile and can cause swelling, inflammation, and infection[7]. Liver diseases such as hepatitis (inflammation of the liver), cirrhosis (severe scarring of the liver), and infections with certain parasites can also contribute to the development of bile duct cancer. In some regions, infection with liver fluke parasites is a major risk factor[2][6].
Additional risk factors include older age, weighing more than is considered healthy, and having a family member with cholangiocarcinoma. People with certain genetic or metabolic conditions affecting the liver may also be at higher risk[6].
Symptoms
Cholangiocarcinoma often does not cause noticeable symptoms in its early stages. Symptoms typically appear only after the cancer has grown large enough to block a bile duct. When symptoms do occur, they can include jaundice, which is a yellowing of the skin and the whites of the eyes. This happens because bile cannot flow properly and builds up in the body[2][4][13].
Other common symptoms include dark-colored urine and light-colored or greasy stools, which are also related to problems with bile flow. Many patients experience itchy skin, a result of bile components accumulating in the body. Abdominal pain, particularly concentrated in the right side of the abdomen underneath the ribs, can occur, especially if the tumor is large. Some people may also experience fever, fatigue, nausea, vomiting, and unexplained weight loss[2][4][6][13].
These symptoms can be caused by many conditions, not just bile duct cancer. However, if you experience any of these signs, it is important to see a healthcare provider to determine the cause. Early evaluation can lead to earlier diagnosis and potentially more treatment options.
Prevention
Because the exact causes of cholangiocarcinoma are not fully understood, there are no guaranteed ways to prevent the disease. However, addressing risk factors and maintaining overall liver health may help reduce the likelihood of developing bile duct cancer.
Managing underlying liver conditions is important. If you have chronic liver disease, hepatitis, or inflammatory bowel disease, working closely with your healthcare provider to control these conditions may be beneficial. Avoiding infections with liver fluke parasites, particularly in regions where these infections are common, can also help. This involves ensuring that food, especially fish, is properly cooked and that water sources are safe.
Maintaining a healthy body weight through balanced nutrition and regular physical activity may also contribute to overall liver health. Limiting alcohol consumption and avoiding tobacco use are general measures that support liver function and reduce the risk of many diseases.
Currently, there is no routine screening test recommended for cholangiocarcinoma in the general population. However, people with known risk factors, such as primary sclerosing cholangitis, may benefit from closer monitoring by their healthcare team[4].
Pathophysiology
Cholangiocarcinoma arises from the cells that line the bile ducts. The bile ducts form a network of tubes that carry bile, a digestive fluid produced by the liver, to the gallbladder and small intestine. Bile helps break down fats during digestion[1][4].
When abnormal changes occur in the DNA of bile duct cells, these cells can begin to grow and divide uncontrollably. Over time, the accumulation of abnormal cells forms a tumor. More than 95 percent of cholangiocarcinomas are classified as adenocarcinomas, a type of cancer that originates in glandular tissue[3].
Cholangiocarcinoma is classified by its location within the bile duct system. Intrahepatic cholangiocarcinoma forms in the bile ducts inside the liver. Perihilar cholangiocarcinoma, also called a Klatskin tumor, occurs just outside the liver where the smaller bile ducts merge to form a larger duct. This is the most common type of cholangiocarcinoma. Distal cholangiocarcinoma forms in the portion of the bile duct closer to the small intestine, outside the liver[1][2][4].
Because cholangiocarcinoma is an aggressive cancer, it spreads quickly. By the time many patients are diagnosed, the cancer has already spread beyond the bile ducts, making it more difficult to treat. Nearly 75 percent of patients have cancer that cannot be surgically removed or that has spread to other parts of the body at the time of diagnosis[3].
As the tumor grows, it can block the bile ducts, preventing bile from flowing normally. This blockage leads to a buildup of bile in the liver and bloodstream, causing jaundice and other symptoms. The cancer can also invade nearby tissues and organs, and cancer cells can break off from the original tumor and travel through the bloodstream or lymphatic system to form new tumors in distant parts of the body, a process called metastasis[8].
