Therapeutic approaches for bone sarcomas

Bone sarcomas include a wide variety of primary, non-epithelial, malignant neoplasms originating from bone cells or their precursors. By definition, they have a potential for metastasis. Some bone sarcomas are purely osteolytic, while others produce a calcified matrix (e.g. osteosarcoma), a cartilaginous matrix (e.g. chondrosarcoma), or a mixed osteolytic/osteoblastic matrix. The three main bone sarcomas include osteosarcoma, Ewing sarcoma and chondrosarcoma. Most bone sarcomas occur in children and young adults and develop in the extremities, especially the distal femur, or the pelvis. The most common symptoms are pain and an enlarging mass. The location, depth and size of an enlarging mass can be determined on physical examination. The presence of persistent non-mechanical pain in any bone lasting more than a few weeks should cause concern and lead to further immediate investigation. A palpable mass will only be present if the tumor has progressed through the cortex and distended the periosteum. Radiographs are important in any patient with prolonged bone pain. Conventional radiographs in two planes should always be the first investigation; a bone sarcoma will almost always be obvious in radiographs. Magnetic resonance imaging is the primary imaging method for evaluating bone lesions, their exact location, and their proximity to neurovascular structures. General staging including bone scintigraphy, chest radiographs and CT should be carried out to assess the extent of distant disease. The majority of patients with bone sarcomas require a multidisciplinary approach that includes orthopedic, medical and radiation oncologists, plastic surgeons, pathologists, and radiologists with expertise in bone tumors. Surgery is the primary therapeutic approach. The role of chemotherapy and radiation therapy is individualized. For some bone sarcomas, such as osteosarcoma and Ewing sarcoma, there is a preference to treat the patient with chemotherapy at the beginning of the course, prior to surgical treatment, aiming to treat the potential micrometastatic disease, reduce the soft tissue mass about the bone tumor and/or mature the mass, allowing for easier resection.