Survey of thorotrast-associated liver cancers in Japan.
Data on 93 autopsy cases (group A) of thorotrast-associated liver cancers were obtained from the "Annual of Pathological Autopsy Cases in Japan" from 1958 to 1979, and data on 78 autopsy cases (group B) of thorotrast-associated liver cancers were obtained from the Japanese literature from 1953 to 1980. Cholangiocarcinoma (CLC) constituted 58% of group A and 55% of group B. The curve of the cumulative numbers of patients with CLC versus year in group A was almost linear, showing an increasing risk per surviving patients with advancing time. Angiosarcoma (AGS) occurred in 25% of group A and 24% of group B. The number of patients with AGS increased significantly after 1969 in both groups (P less than 0.05). In group B, age and years after thorotrast injection of patients with AGS were statistically higher than those of patients with CLC (age: P less than 0.05; years after thorotrast injection: P less than 0.0001). Hepatocellular carcinoma (HPC) accounted for 17 and 21% of groups A and B, respectively. When yearly distribution, age, and time after thorotrast injection of patients with HPC were correlated with those of patients with other liver cancers, the only statistically significant difference between patients with HPC and patients with CLC (P less than 0.02) was in the years after thorotrast administration. Since 1977 multiple primary liver cancers including AGS developed in thorotrast-administered patients in both groups.