A parasite in raw fish helps explain where bile duct cancer clusters
Bile duct cancer is rare in Western countries, at roughly 0.5 to 2 cases per 100,000 people a year. In parts of Thailand the rate reaches 60. Much of that gap traces to liver flukes picked up from raw or undercooked food, and campaigns against eating it have cut cases.
Cholangiocarcinoma is a cancer arising in the ducts that carry bile. It usually takes the form of an adenocarcinoma, meaning its cells form glands or produce mucin. Warning signs can include yellowing skin, belly pain, weight loss, itching and fever, along with pale stools or dark urine. Location matters: tumours in the ducts outside the liver more often block bile and cause jaundice, while those inside the liver tend to cause pain without it. Itching affects around two thirds of patients.
Most people who develop it have no known risk factor. The best-known in the West is primary sclerosing cholangitis, an inflammatory bile duct disease closely tied to ulcerative colitis; studies put the lifetime risk for such patients at about 10 to 15 percent, and autopsy series have found up to 30 percent. Chronic liver damage from hepatitis B or C, alcohol or cirrhosis raises the risk too. In Southeast Asia and East Asia the flukes Opisthorchis viverrini and Clonorchis sinensis are linked to the disease.
Doctors suspect it from a mix of blood tests, imaging and endoscopy, and confirm it by looking at tumour cells under a microscope. Liver blood tests often show an obstructive pattern: bilirubin, alkaline phosphatase and gamma-glutamyltransferase run high while transaminases stay near normal, pointing to a blockage rather than inflamed liver tissue.
By the time it is found, the cancer usually cannot be cured, which is why catching it early matters so much. In roughly a third of cases involving the common bile duct, surgeons can remove the whole tumour, and occasionally a liver transplant is part of the operation. Even then, fewer than half of patients typically survive five years. It most often appears in people in their seventies, but in those with primary sclerosing cholangitis it tends to strike in their forties, and cases arising inside the liver have been rising in Western countries.
Source: Cholangiocarcinoma
