A nurse is conducting a staff in-service on childhood cancers. Which is the primary site of osteosarcoma?

A. Humerus is incorrect because although osteosarcoma can occasionally affect the humerus, it is not the most common site. Upper extremity involvement is less frequent in pediatric patients. B. Femur is correct because osteosarcoma most commonly arises in the metaphyseal region of long bones, particularly around the distal femur, which accounts for approximately 50% of cases. This site is prone to rapid bone growth, which is associated with tumor development. C. Tibia is incorrect because while the tibia is a site for osteosarcoma, it is the second most common site, after the femur. Incidence in the tibia is lower compared to the distal femur. D. Pelvis is incorrect because osteosarcoma rarely originates in flat bones such as the pelvis in children. Pelvic involvement is uncommon and usually occurs in older adolescents or adults.