Definition
Biliary tract cancer (cholangiocarcinoma) is a rare malignant tumor that develops in the bile ducts. It is classified as intrahepatic (within the liver) or extrahepatic (outside the liver) based on its location.

Pathogenesis
The development of biliary tract cancer is linked to:

• Chronic inflammatory conditions: Such as primary sclerosing cholangitis (PSC).
• Parasitic infections: Certain liver parasites (e.g., Opisthorchis viverrini).
• Other factors: Chronic gallstones, exposure to toxins, and genetic mutations.

Diagnosis
Diagnosis is made using:

• Imaging techniques: Ultrasound, CT, MRI, or MRCP (magnetic resonance cholangiopancreatography) to identify the lesion.
• Laboratory tests: Elevated cholestatic markers (bilirubin, ALP, GGT) and tumor markers like CA 19-9.
• Biopsy or cytology: Confirms the diagnosis.

Treatment
Treatment depends on the tumor’s location and stage:

• Surgical resection: The only curative option for localized disease.
• Liver transplantation: Indicated for select extrahepatic cholangiocarcinomas in clinical trial settings.
• Adjuvant therapy: Chemotherapy or radiotherapy for unresectable cases or to reduce recurrence risk.
• Targeted therapies: Used for cases with specific genetic mutations.

Prevention
Prevention includes:

• Treatment of parasitic infections.
• Management of chronic conditions: Such as PSC.
• Avoiding toxins and periodic screening in high-risk individuals.

Early diagnosis is challenging due to a lack of early symptoms but is crucial for improving survival. In advanced stages, treatment focuses on symptom management and improving quality of life.