Exostoses induced by 224Ra (ThX) in children.

Exostoses are benign cartilaginous tumors of bone. They can occur naturally or be induced by radiation therapy during the time of skeletal growth. We have observed exostoses in 28 of 218 children given repeated injections of radioactive bone-seeking 224Ra. The younger the age at irradiation, the higher the incidence of exostoses. Boys are more susceptible than girls. To our knowledge, none of these radiation-induced exostoses have become malignant, although 36 of these children have developed bone sarcomas elsewhere in the skeleton.