Hepatic neoplasms from internally deposited 144CeCl3.

Fifty-five dogs were exposed by inhalation to graded activity levels of 144CeCl3, a relatively soluble form of the beta-emitting radionuclide. A large portion of the 144Ce translocated from lung to liver and skeleton. Significant radiation doses were delivered to the respiratory tract, liver, and skeleton; however, the liver received the greatest cumulative absorbed dose. Liver tumors were the most frequently observed neoplasms in these exposed dogs and included 7 primary hepatic hemangiosarcomas, 1 cholangiocarcinoma, 1 hepatocellular carcinoma, 1 fibrosarcoma, 4 biliary cystadenomas, and 1 fibroma. The dose to the liver in these dogs ranged from 11 to 250 Gy with a median of 57 Gy. Autoradiographs showed a relative uniform distribution of beta dose to the liver. All the malignant tumors and 1 cystadenoma were primary causes of death. The morphologic features of the hemangiosarcomas and associated hepatic lesions were similar to those described for hemangiosarcomas induced in people exposed to Thorotrast. Biliary cystadenomas were associated with degenerative lesions in the liver but not with other neoplasms in the liver. These results indicate that the liver is an important target organ for effects from internally deposited 144Ce.