Sites of incidence of osteosarcoma in the long bones of man and the beagle.

Information has been assembled on the frequency of occurrence of osteosarcomas in the long bones of groups of beagles irradiated by alpha particles from bone-seeking radionuclides. These data are compared with measured trabecular surface areas in the long bones of a beagle, determined at the Bone Dosimetry Research Laboratory, Cookridge Hospital, Leeds. It is shown that, as in the human case, the percentage tumour occurrence in a long bone (or in separate thirds of a long bone) was linearly related to the corresponding trabecular surface area with a high value of the correlation coefficient. For single injections of 226Ra the low percentage tumour occurrence in the mid-thirds of the beagle bones was close to that found in man. For the surface-seeking radionuclides (239Pu, 228Th) and for 228Ra much higher percentages of tumours were found in the mid-thirds of the dog bones than for 226Ra injection. When, however, 226Ra was given in eight fractions with 14 days between each injection, a very high tumour incidence was found in the mid-thirds of the beagle long bones. These results are discussed in the light of dosimetric and other relevant factors.