Thorotrast induced liver cancer: Update of the German Thorotast study

The German Thorotrast study was started in 1968. It comprises 2,326 Thorotr ast patients and 1,890 contemporary matched controls. 899 Thorotrast patien ts and 662 patients of the control group have been examined clinically and biophysically every two years. The evaluation of the causes of death demons trates a statistically significant excess rate of malignant liver tumors, l iver cirrhoses, myeloid leukaemias and bone marrow failures. The annual dos e after an injection of two ampoules (24 ml) is about 25 cGy for the liver, 70 cGy for the spleen and 9 cGy for the bone marrow Animal experiments dem onstrated that non-radiation effects can be neglected. Correlation exists b etween the calculated dose to the liver and the frequency of liver cancer T he cumulative risk estimate for liver cancer of about 600 per 10(4) PGy com es close to the values which were calculated based on the epidemiological r esults of the Japanese bomb survivors when a quality factor of 20 for alpha -radiation and a low dose rate reduction factor of 2 were applied. Dose and frequency of liver cirrhosis are also correlated. Liver cirrhosis is often combined with liver cancer but is not a prerequisite for tumor induction.