HIGH-FREQUENCY OF LEUKEMIC LYMPHOMAS WITH OSTEOSARCOMAS BUT NO MYELOID LEUKEMIAS IN C3H MICE AFTER PU-239 CITRATE INJECTION

Female C3H strain mice, which do not spontaneously exhibit frequent bo ne tumors and myeloid leukemias, were injected intraperitoneally with various doses of 10 to 12000 Bq/animal of monomeric Pu-239 citrate to clarify lifetime carcinogenesis caused by alpha-particles distributed mainly in the skeleton, Survival time was reduced significantly at mea n skeletal doses of more than 2.93 Gy and was accompanied by marked li fe-shortening as compared to the controls due to an earlier increase i n neoplastic or non-neoplastic death. Bone tumors, almost ail of which were osteosarcomas, were not found in the controls, whereas their inc idence 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 presen t in 20% of the control animals, their incidence dropped to zero at 6. 92 Gy, then increased al higher doses (36% at 25.5 Gy). Non-thymic, mo stly pre-B cell type, leukemic lymphomas mainly occurred at early time after Pu-239-injection; whereas, in the controls thymic, lymphocytic or histiocytic lymphomas occurred only at a later time. Of the other s oft tissue tumors, neither myeloid leukemias nor myelogenous neoplasms were found in the controls or the Pu-239-injected animals. Tumors aff ecting the lungs, liver, ovaries, and skin were much fewer or not foun d at mean doses of more than 2.93 Gy. These results indicate dose-depe ndent, differential tumor induction resulting from bone and lymphoid t umor competition after an injection of plutonium.