Thorotrast-Induced Carcinoma of the Liver

I. Introduction Thorotrast was first employed clinically in 1928 by Blühbaum, Frik, and Kalkbrenner.1During the period from 1930 to 1950, it was used widely in Europe and to a lesser extent in the United States for visualization of cavity spaces, cerebral angiography, and visualization of the reticuloendothelial system. Thorotrast utilization has been curtailed in the last decade because of the immediate sequelae of induration at the site of injection, because of granuloma formation when injected interstitially, and particularly because of increasing evidence of the delayed sequelae of irradiation-induced malignant neoplasms.2,3 Thorotrast is a colloidal solution of thorium dioxide (ThO2) of about 20% by weight in invert carbohydrate solution. Thorium dioxide (Thorotrast) has a particulate size of 3 to 10 mμ, and parent Th232has a half-life of 1.39 × 1010years. Tumors have occurred at the site of injection of Thorotrast when used for