Osteosarcoma is the most common primary malignant bone tumor seen in children and young adults. It is described as an aggressive neoplasm that arises from primitive transformed cells of mesenchymal origin.
Key Characteristics and Demographics
- Target Populations: While most common in younger populations, it can also develop in adults over 65 as a secondary malignancy related to Paget’s disease of the bone.
- Common Sites: It often presents in the long bones, such as the tibia or femur near the knee.
- Diagnosis: If suspected, a biopsy must be performed by an experienced surgeon or radiologist to minimize the risks of pathologic fracture or tumor seeding.
Treatment Overview
The management of osteosarcoma typically requires a multimodal approach:
- Surgery: This is a cornerstone of therapy. Limb-sparing procedures are preferred when feasible, while amputation is reserved for cases where limb-sparing is not possible or if a prosthesis would provide better functional independence.
- Chemotherapy: Osteosarcoma is highly sensitive to chemotherapy, which improves cure rates to upwards of 75% when combined with surgery. Standard first-line regimens often include cisplatin and doxorubicin (AP) or a three-drug combination known as MAP (methotrexate, doxorubicin, and cisplatin).
- Radiation: The disease is relatively resistant to radiation, meaning its role is generally limited to palliation or specific cases where a tumor is unresectable.
Prognosis and Metastasis
A patient’s outlook is influenced by several factors, including the size and site of the tumor, the completeness of surgical resection, and the patient’s age (outcomes are generally worse for those over 40). A critical prognostic indicator is the histologic response to neoadjuvant chemotherapy; a “good” response is defined as greater than 90% tumor necrosis observed in the surgical specimen. If metastasis occurs, it most frequently involves the lungs (90%) and other bones (10%).