Cancer mortality in Thorotrast-exposed patients in Japan: Aichi series

Abstract

Background. To evaluate the late effect of internally deposited alpha emitters in humans, we performed, during the period 1979-1992, a follow-up study of patients who had received intravascular injections of Thorotrast (thorium dioxide) 30-50 years previously. The study was performed independently of and with no overlap of subjects in the previous Japanese study by Mori and coworkers. Methods. The patients were 198 war-wounded veterans with intrahepatic and splenic Thorotrast deposits that were detected by abdominal X-ray examination during the period 1975-1978. Results. During our observation period (1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992), 143 of 198 patients (1526 person-years) who had had Thorotrast injections died. Conclusion. Compared with 1113 war-wounded veterans with no history of Thorotrast injection, the Thorotrast-exposed patients had a 3.1-fold greater risk of death from all causes (95% confidence interval, 2.6-3.8), a 45.3 times greater risk of liver cancer (95% confidence interval, 24.8-82.5), and a 5.1 times greater risk of liver cirrhosis (95% confidence interval, 1.9-14.1).