Investigations of ⁹⁰Sr in Dogs: I. Pathogenesis of radiation-induced bone tumors

Abstract

Purebred beagle dogs given ⁹⁰Sr and unirradiated controls were studied for over two decades. Pregnant females were fed different doses of ⁹⁰Sr from day 21 post-conception until the offsprings reached an age of 540 days. In an additional experiment two dose levels were given in a single intravenous dose to dogs 540 days old. Radio-graphically the earliest skeleton lesions were characterised by small linear, solitary, cortical lucencies. These as well as tumors were more frequently noted in the higher exposure levels. They affected the appendicular skeleton almost as frequently as the axial skeleton. The lesions were predominantly found in the diaphysis, at the angle and near the acetabulum in the tubular bones, mandible and pelvis, respectively. The lesions within the diaphysis originated in the cortical bone. Histologically these lesions were characterised by different types of porosities. These could be empty or filled by a defect and/or immature, dysplastic fibrous repair tissue, within the frame of which malignant transformations seemed to take place as evidenced by malignant clones and microosteosarcomas. A comparison is made of the histologic events in dogs and mice and a tentative pathogenesis of ⁹⁰Sr induced bone tumors is discussed.