Risk factors, epidemiology and prognosis of cholangiocarcinoma in Finland

Background: Cholangiocarcinoma (CCA) is a cancer arising from the intra- and extrahepatic bile ducts. The early stages are often asymptomatic, CCA is frequently diagnosed in an advanced stage and the prognosis of CCA is often dismal. Objective: Our objective was to estimate the incidence of CCA in Finland and to identify risk factors for CCA, with a special interest in primary sclerosing cholangitis (PSC). Methods: We identified all CCA cases during 1974-2018 from the Finnish Cancer Registry and calculated age-standardised incidence rates. Five controls for each case were extracted from the Population Registry, matched by age, gender and municipality of residence at the time of diagnosis. Odds ratios (ORs) for risk factors were estimated with conditional logistic regression and survival estimates with the Kaplan-Meier method. Results: Incidence of CCA remained stable in both genders; the age-standardised rate (World Standard) in 2013-2017 in males and females was 1.7 per 100,000 person years and 1.3 per 100,000 person years, respectively. Primary sclerosing cholangitis carried a 30-fold risk of intrahepatic cholangiocarcinoma (iCCA) and 25-fold risk of extrahepatic cholangiocarcinoma (eCCA). Diabetes, inflammatory bowel disease and liver cirrhosis were associated with iCCA, whereas cholelithiasis and viral hepatitis C were associated with eCCA. The cumulative 5-year survival was 4.6%. Conclusions: The incidence of CCA has been stable. Known risk factors for CCA were confirmed, with PSC having the highest OR. Survival remains poor.