Osteosarcoma induced by short-lived bone-seeking. cap alpha. emitters in mice: the role of age. [/sup 224/Ra, /sup 227/Th]

In three experiments with low, medium, and high osteosarcoma expectancy after incorporation of /sup 224/Ra or /sup 227/Th the osteosarcoma risk of adult (5-6 months old) female NMRI mice was compared with that of rapid growing (1 month old) animals. Similar to results in the literature with other bone-seeking radionuclides the age-corrected osteosarcoma incidence was not significantly different in both age groups. In the experiment with high osteosarcoma risk the time of tumor appearance was mainly determined by the time of start of the internal irradiation period. It seems that at lower osteosarcoma expectancy the time of appearance of the tumors is mainly determined by the age of the animals.