Extrahepatic Bile Duct Carcinoma

Introduction

The bile duct is the connecting tube from the stomach to the liver. Based on the origin of the site of the lesion, these cancer cells are named extrahepatic, meaning the outer surface and distal hepatic, signifying distal location.

What Exactly Is Cholangiocarcinoma?

A uncommon kind of cancer called cholangiocarcinoma develops in the bile ducts of the body. The bile (a fluid that aids in food digestion) is transported to the small intestine by bile ducts, which are tiny tubes in the liver and gallbladder.

The majority of patients with cholangiocarcinoma are diagnosed after the disease has already left their bile ducts. Treatment is challenging, and chances of recovery are typically slim. Clinical studies and an increasing number of targeted medicines are beginning to alter that, though.

Cholangiocarcinoma is classified into three types, namely:

• Intrahepatic cholangiocarcinoma

• Gall bladder cancer.

• Extrahepatic cholangiocarcinoma.

What Is Extrahepatic Bile Duct Carcinoma?

Extrahepatic cholangiocarcinoma is bile duct cancer that occurs outside of the liver. The ducts that leave the liver or that end in the small intestine may both contain cancer. The most typical form of bile duct cancer is this one. Hilar cholangiocarcinoma, or bile duct cancer that originates in the hilum, the region where the bile ducts and significant blood arteries link with the liver, is a subtype of extrahepatic cholangiocarcinoma.

What Causes Bile Duct Cancer?

The exact cause of such a condition is still unknown. However, situations that can provoke such abnormal proliferation of cells are:

• Gene Mutations: Abnormal cell proliferation can accumulate and cause tumor formation.

• Alcoholic Liver Disease: This can lead to inflammation of the liver.

• Smoking: This can create abnormal stress in the cells and hence cause the proliferation of bile duct cells.

• Chronic Liver Diseases: These are also known as end-stage diseases. Other viral infections and cirrhosis of the liver can also affect the liver cells and trigger the proliferation of cells.

• Infections: Disease caused due to liver parasites can damage the cells.

• Congenital: Cysts formed due to congenital problems such as choledochal cysts in children.

• Ulcers: Injury to the lining cells of the bile duct causing ulcerative colitis.

• Chemicals: Exposure to chemicals can cause cholangiocarcinomas. Such as chemicals used in aircraft manufacturing.

Who Are More at a Risk of Developing Bile Duct Cancer?

As discussed, it is the rarest form of cancer and is seen among the following population. Such as:

• Older patients.

• Smoking.

• Seen more in men than women.

• Patients with existing infections.

• Having a history of primary sclerosing cholangitis.

• Conditions like inflammatory bowel disease.

What Are the Signs of Bile Duct Cancer?

Some of the symptoms seen in bile duct cancer are:

• Jaundice.

• Gall bladder stone.

• Discoloration of stools.

• Nausea.

• Vomiting.

• Weight loss.

• Inflammation of the liver.

• Inflammation of the pancreas.

• Abdominal pain.

• Fatigue.

• Itchy skin.

• Fever.

What Are the Differences Observed in the Tissue Structure of Bile Duct Cancer?

Many variations have been observed in the tissue architecture. Some pathological changes are squamous cell differentiation, irregular border, fibrous lesions, and tumor formation. Apart from this, in about 50 percent of cases, hepatomegaly is seen, and in about 25 percent of cases swelling in the gallbladder, which is palpable, is observed.

What Are the Biochemical Changes Seen in Bile Duct Cancer?

The change in the cellular pattern also has a definite effect on its secretory activity.

• Increased production of serum alkaline phosphatase in the blood is seen.

• Increased secretion of aminotransferases.

• The presence of bile in the urine is observed.

• A prolonged prothrombin time.

What Are the Complications Seen in Bile Duct Cancer?

Certain complications which can go neglected can often develop or trigger other malignancies. One such malignancy seen is the tumor of the gall bladder, which can develop into an abnormal proliferation of cells. In addition, the presence of jaundice for a more extended period can also give way to cellular differentiation.

How Is the Prognosis of Bile Duct Cancer?

Depending on the lesion size, the prognosis can be made. Mostly they are small tumors limited within the bile duct. Despite being small, they are difficult to remove during surgical procedures. The survival rate is 6 - 18 months post-surgery.

How to Diagnose Bile Duct Cancer?

Diagnosis can be made based on the elicited symptoms. Tests conducted are:

• Blood Test: To check for the raised serum alkaline phosphatase, aminotransferases, and increased prothrombin time.

• Tumor Marker Test: It helps to check the level of tumor antigen- CA-19 in the blood.

• Endoscopic Retrograde Cholangiopancreatography (ECRP): This test is done to check the areas of the bile duct which connect to the small intestine. This procedure is carried out by injecting a dye into the vessels for proper visualization. Such imaging tests help in other tests like computed tomography (CT) and magnetic resonance imaging (MRI).

• Biopsy: If any area of abnormality is detected, a biopsy sample is collected, and a microscopic study is done.

What Are the Available Treatment Option for Bile Duct Cancer?

The cure for bile duct cancer depends on the location of the cancer and its extent. Some of the treatment options available are:

• Surgery: Surgical resection of the tumor. Though complete resection of the tumor is difficult in bile duct cancer, partial removal of liver tissue, pancreatic tissue, and complete removal of lymph nodes are done. In hilar cancer, complete removal of the liver is done, and new tissue is transplanted from a donor.

• Photodynamic Therapy: This procedure is done to shrink the tumor and control its growth.

• Radiation Therapy: High radiation is induced at the site of the lesion to kill the cancer cells.

• Chemotherapy: Chemicals are used to kill cancer cells. It can be used orally or intravenously.

• Biliary Drainage: This is done to restore the flow of bile or bile duct secretion and reduce the symptoms.

Conclusion:

Bile duct cancers are a slow-progressing condition; their prognosis is not good. In addition, the survival rate after the surgery is also not seen to improve. They are the rarest form of cancer and do not have any specific blood tests to detect the presence of malignancy. Hence, early detection is made difficult.