K. Hemminki, F. Tichanek, A. Försti, O. Hemminki, V. Liska, A. Hemminki: Long- term incidence in hepatocellular carcinoma and intrahepatic bile duct cancer in Denmark, Finland, Norway and Sweden, role of Thorotrast? Int J Cancer. 2022 Apr 16. doi: 10.1002/ijc.34031.
We analyzed long-term incidence trends in liver cancer (including hepatocellular carcinoma and intrahepatic cholangiocarcinoma) to interpret the changes in terms of known risk factors and hypothesize that historical exposure to Thorotrast, a radiographic contrast medium emitting alpha particle, has changed population rates. The NORDCAN database was used to collect cancer registry data from Denmark (DK), Finland (FI), Norway (NO), and Sweden (SE), which we used from 1953 (DK, FI, NO) and 1960(SE) through 2019. Thorotrast, which caused a 100-fold risk of liver cancer was used in DK and SE, and probably also in FI between 1930 and 1950, but not in NO. The incidence trend for liver cancer showed a broad maximum at around 1980, most prominent and statistically significant in SE and DK men and women. In all countries, a steadily increasing trend towards the end of follow-up. Incidence for NO was lower than for the other countries and the rates showed no peaking at around 1980. Birth cohort analysis identified a transient risk that could be dated to a period between 1930 and 1950 in countries other than NO. Considering a lag time between Thorotrast use and liver cancer appearance, the large incidence peak around 1980 in DK and DE was probably contributed by Thorotrast but considering the ecological nature of the findings, the association should be considered cautiously as hypothesis-generating. The late increase in liver cancer risk is most likely lifestyle-related and largely preventable. In addition, according to this article, similar population-level risks were also observed for gallbladder and bile duct cancers, with additional effects of decreased survival.
(A vial of Thorotrast contrast medium and a radiogram on tumors that it induced)