High frequency of leukemic lymphomas with osteosarcomas but no myeloid leukemias in C3H mice after 239Pu citrate injection.

Abstract

Female C3H strain mice, which do not spontaneously exhibit frequent bone tumors and myeloid leukemias, were injected intraperitoneally with various doses of 10 to 12,000 Bq/animal of monomeric 239Pu citrate to clarify lifetime carcinogenesis caused by alpha-particles distributed mainly in the skeleton. Survival time was reduced significantly at mean skeletal doses of more than 2.93 Gy and was accompanied by marked life-shortening as compared to the controls due to an earlier increase in neoplastic or non-neoplastic death. Bone tumors, almost all of which were osteosarcomas, were not found in the controls, whereas their incidence increased sharply to a maximum of 96% at 6.92 Gy, then dropped at higher doses (20% at 42.4 Gy). Although lymphoid tumors were present in 20% of the control animals, their incidence dropped to zero at 6.92 Gy, then increased at higher doses (36% at 25.5 Gy). Non-thymic, mostly pre-B cell type, leukemic lymphomas mainly occurred at early time after 239Pu-injection; whereas, in the controls thymic, lymphocytic or histiocytic lymphomas occurred only at a later time. Of the other soft tissue tumors, neither myeloid leukemias nor myelogenous neoplasms were found in the controls or the 239Pu-injected animals. Tumors affecting the lungs, liver, ovaries, and skin were much fewer or not found at mean doses of more than 2.93 Gy. These results indicate dose-dependent, differential tumor induction resulting from bone and lymphoid tumor competition after an injection of plutonium.