Cholangiocarcinoma is a cancer that arises from the cells lining the bile ducts. It is rare. Where it sits determines how it behaves and how it is treated, so it is classified by location. Intrahepatic cholangiocarcinoma develops within the liver itself. Hilar cholangiocarcinoma, sometimes called a Klatskin tumour, develops where the ducts converge as they leave the liver, and it is both the most common form and the most technically demanding to treat because it lies immediately alongside the hepatic artery and portal vein. Distal cholangiocarcinoma develops in the lower part of the duct, near the pancreas, and is treated much like a pancreatic head tumour. Risk factors include primary sclerosing cholangitis, choledochal cysts, chronic liver disease and certain parasitic infections, though many people who develop it have no identifiable risk factor.

The commonest presentation is painless jaundice, a yellowing of the eyes and skin caused by the tumour obstructing the bile ducts. It is often accompanied by dark urine, pale stools, and itching that can be severe and is frequently what prompts people to seek help. Other symptoms include unexplained weight loss, loss of appetite, fatigue, and discomfort in the upper right abdomen. Fever with jaundice suggests infection in the obstructed ducts and needs urgent assessment. Because the early stages often produce no symptoms at all, the disease is frequently identified only once the duct is blocked, which is one of the reasons it is difficult to treat.

Diagnosis usually begins with blood tests and imaging, typically a CT scan and an MRCP, a form of MRI that maps the bile ducts in detail. Getting tissue is the harder part. Cholangiocarcinoma provokes a dense inflammatory reaction in the tissue around it, which means conventional brush samples and needle biopsies frequently come back negative even when cancer is present. For that reason a fine camera is passed directly into the bile duct during ERCP so the tumour can be seen and sampled directly with tiny forceps. The same procedure can relieve the obstruction by placing a stent. Once the diagnosis and the extent of disease are established, the case is reviewed by a multidisciplinary team including an HPB surgeon, a medical oncologist, a radiation oncologist and a radiologist, who together plan treatment.

Surgery offers the only realistic prospect of cure, and whether it is possible depends on where the tumour sits and how far it extends. Tumours within the liver are treated by removing the affected part of the liver. Tumours at the hilum may require removal of the bile ducts together with a section of liver, and reconstruction of the drainage into the intestine. Tumours in the lower duct are usually treated with a Whipple procedure. Because the liver must be left with enough healthy tissue to function, preparation sometimes involves procedures to relieve jaundice or to encourage the remaining liver to grow before surgery. Chemotherapy is used alongside surgery, and where the tumour cannot be removed, treatment focuses on chemotherapy and on relieving the obstruction with stents so that symptoms improve and quality of life is preserved.

It depends heavily on where the tumour is, how far it has spread, and whether it can be removed completely, and it is worth being honest that the outlook for this cancer is generally poor. Most cases are found at a stage where surgery is not possible, and for those patients treatment aims to control the disease and relieve symptoms rather than to cure. Where the tumour can be completely removed, long-term survival is a genuine possibility, and outcomes are best when the margins are clear and the lymph nodes are not involved. Distal tumours, which are treated like pancreatic head tumours, generally carry a better outlook than hilar ones. These are population patterns and no figure predicts an individual case, which is why the specifics of your imaging and pathology matter far more than any general statistic.