Danish epileptics given Thorotrast

Cancer incidence among 8004 patients hospitalized for epilepsy between 1933 and 1962 was compared to that of the general population. Among 140 epileptics given Thorotrast during cerebral angiography, a significant excess of cancer was observed (relative risk (RR) = 4.9), whereas the RR among the other 7864 patients was only 1.19. Thorotrast exposure was linked to significant excess of liver cancer (RR = 202, n=17), leukaemia (RR = 17, n = 5) and lung cancer (RR = 3.2, n = 5). Brain tumours observed appeared to be linked to the epilepsy rather than Thorotrast. Haemangiosarcomas of the liver appeared uniquely related to Thorotrast, as did the rare subtypes of leukaemia. Cholangiocarcinomas also occurred in excess. The preponderance of anaplastic lung cancer is provocative and suggests Thorotrast decay might be involved. The cumulative risk (± SE) of developing cancer at 40 years, excluding brain cancer risk, was 60 ± 6%. (author)