Osseous Changes and Osteosarcomas In Mice Continuously Fed Diets Containing Diethylstilbestrol or 17β-Estradiol

In a study on the long-term effects of dietary diethylstilbestrol or 17β-estradiol on C3H mice. estrogens induced a proliferation of osseous trabeculae and increased the incidence and hastened the development of osteofibrotic areas in the sterna. There were 6 osteosarcomas. 2 having metastases. in 1.242 mice fed dietary estrogens over 360 days. but none in 356 untreated controls. These tumors were reviewed along with 4 early sternal osteosarcomas selected from 17 osteosarcomas (only 1 in a control) found thus far in two other ongoing comparable studies. In at least 1 case. and possibly in 2 other early cases. tumors were associated with areas of osteofibrosis. and 1 tumor was probably associated with proliferation of bony trabeculae in the medullary cavity.