What is bile duct cancer?

What is bile duct cancer? Many people don't know much about bile duct cancer. Many patients are already in the late stage when they are diagnosed with the disease. Biliary duct cancer is a disease that needs to be taken seriously because it threatens the life and health of patients. Today we would like to introduce to you some common knowledge about bile duct cancer. Let's take a look.

Cholangiocarcinoma refers to a malignant tumor of the extrahepatic bile duct that originates from the confluence of the left and right hepatic ducts to the lower end of the common bile duct. Cholangiocarcinoma can be divided into three types: hilar cholangiocarcinoma or upper cholangiocarcinoma, middle cholangiocarcinoma, and lower cholangiocarcinoma. Primary cholangiocarcinoma is rare, accounting for 0.01% to 0.46% of ordinary autopsies, 2% of autopsies of tumor patients, and 0.3% to 1.8% of biliary surgeries. In Europe and the United States, gallbladder cancer is 1.5 to 5 times that of cholangiocarcinoma, while Japanese data show that cholangiocarcinoma is more common than gallbladder cancer. The male-to-female ratio is about 1.5 to 3.0. The age of onset is mostly 50 to 70 years old, but it can also be seen in young people. Cholangiocarcinoma can occur in various parts of the extrahepatic bile duct, among which the proximal bile duct (hilar bile duct) is the most common, accounting for about 58%, the middle and distal bile ducts account for 13% and 18% respectively, and those that occur in the cystic duct account for 4%, and another 7% are diffuse.

The cause of bile duct cancer is still unclear, but it has been found to be related to the following factors:

1. Chronic inflammation and infection of the bile duct Long-term chronic inflammation is the basis for the occurrence of bile duct cancer, because clinically found that diseases related to bile duct cancer can lead to chronic inflammation of the bile duct. Certain substances in the bile (such as the metabolites of bile acid) stimulate the bile duct mucosa for a long time, leading to atypical hyperplasia of the epithelium.

2. Bile duct and gallbladder stones 20% to 57% of bile duct cancer patients have gallstones, so it is believed that chronic stimulation by stones may be a carcinogenic factor.

3. Ulcerative colitis: It has been reported that the incidence of bile duct cancer in patients with ulcerative colitis is 10 times higher than that in the general population. The age of onset of bile duct cancer patients with ulcerative colitis is 20 to 30 years earlier than that of the general population, with an average age of 40 to 45 years. They often have a long history of colitis. Chronic bacteremia in the portal vein system of patients may be the cause of bile duct cancer and PSC. The lesions often affect the entire colon. Ulcerative colitis-induced bile duct cancer may be related to chronic portal vein bacteremia.

4. Cystic malformation of the bile duct (congenital bile duct dilatation) It has become a consensus that congenital bile duct cysts are prone to cancer. The incidence of bile duct cancer in patients with congenital bile duct cysts is as high as 2.5% to 28%, and patients with bile duct cysts develop cancer 20 to 30 years earlier than normal people. Although 75% of bile duct cysts show symptoms in infancy and childhood, as for the occurrence of bile duct cancer, 3/4 of patients have symptoms of bile duct cysts in adulthood. Regarding the mechanism of bile duct cysts leading to bile duct cancer, some people believe that when the opening of the pancreatic duct into the bile duct is abnormally high, pancreatic fluid will flow back into the bile duct and cause malignant changes in the bile duct epithelium. Other factors that may lead to malignant changes include bile stasis, stone formation, and chronic inflammation in the cyst cavity.

5. Liver fluke (Clorchis sinensis) infection Infection with Clonorchis sinensis is also believed to be related to the occurrence of cholangiocarcinoma. Although Clonorchis sinensis mostly parasitizes in the intrahepatic bile duct, it can also parasitize in the extrahepatic bile duct. The worm itself and its metabolic products cause long-term stimulation to the bile duct mucosal epithelium, causing hyperplasia of the bile duct mucosa, tumor-like changes, and cancer.

In addition, it may be related to pancreatic juice reflux, bile stasis, stone formation, malignant transformation of benign bile duct tumors, and tumor-like differentiation of liver stem cells, all of which can cause chronic inflammatory stimulation of the bile duct mucosa and induce bile duct cancer.

2. Pathogenesis

Cholangiocarcinoma can occur in various parts of the extrahepatic bile duct, with the proximal bile duct (hilar bile duct) being the most common, accounting for about 58%, the middle and distal bile ducts accounting for 13% and 18%, respectively (Figure 1), the cystic duct accounting for 4%, and another 7% being diffuse.

The above is an introduction to common knowledge about bile duct cancer. I hope it will be helpful to you.