[Osteosarcoma in 2 siblings. A case report].

With a brother and sister, osteosarcoma developed at the age of 11 and 14 respectively. With both there was no previous retinoblastoma or other bone disease with a proclivity to develop osteosarcoma. We discuss possible explanations for familial aggregation of osteosarcoma, citing external or genetic factors. We suggest that it is the retinoblastoma gene RB and the tumor suppressor gene p53 which play an important part in the development of osteosarcoma.