Whereas most osteosarcomas occur in patients younger than 25 years, five patients over 50 years with osteosarcoma have been diagnosed and treated at our hospital. Osteosarcomas occuring in older patients are reported to be more frequently secondary to other bony conditions such as Paget's disease, or following irradiation. Two of five were radiation-induced osteosarcomas arising in the pelvis. Three patients were treated by chemotherapy, but this was not effective in two of them. Only one of the five patients is still alive without the disease, while four have died from the disease. Three of these four died within one year after admission.
