The osteosarcomas may be localized at the end of the long bones (commonly in the metaphysis). Most often osteosarcoma affects the upper end of the tibia, humerus, or lower end of the femur. Fifty-six percent of all osteosarcomas present around the knee. The epiphyseal growth plates of the distal femur and proximal tibia are responsible for a great deal of the increase in height that occurs during puberty.
Osteosarcoma in Belgium is very rare in young children (0.5 cases per million per year in children < 5 years). However, the incidence increases steadily with age, rising more dramatically in adolescence in correspondence with the adolescent growth spurt. Patients with osteosarcoma are best managed by a medical oncologist and an orthopedic oncologist experienced in managing sarcomas. Current standard treatment is to use neoadjuvant chemotherapy (chemotherapy given before surgery) followed by surgical resection. The percentage of tumor cell necrosis (cell death) seen in the tumor after surgery gives an idea of the prognosis and also lets the oncologist know if the chemotherapy regimen should be altered after surgery.