Primary Malignant Bone Tumors

Primary malignant bone tumors (sarcomas of the bone) are rare, constituting less than 1% of all malignant tumors. Most bone tumors result from metastasis from another malignant tumor.

Primary bone tumors occur more commonly in males than in females, especially in children and adolescents, although some types occur in people between ages 35 and 60.

Causes

Although the cause of primary malignant bone tumors remains unknown, some researchers hypothesize that primary malignant bone tumors arise in centers of rapid skeletal growth because children and young adults with these tumors seem to be much taller than average. Other theories point to heredity factors, trauma, and excessive radiotherapy as causes.

Prior exposure to carcinogens, an underlying condition such as Paget's disease, or radiation exposure has been linked with the development of osteogenic sarcomas, chondrosarcomas, and fibrosarcomas.

Primary malignant bone tumors may originate in osseous or nonosseous tissue. Osseous tumors arise from the bony structure as well as from cartilage, fibrous tissue, and bone marrow. They include osteogenic sarcoma (the most common), parosteal osteogenic sarcoma, chondrosarcoma (malignant cartilage tumor), and malignant giant cell tumor. Together, these make up about 60% of all malignant bone tumors.

Nonosseous tumors arise from hematopoietic, vascular, and neural tissues. They include Ewing's sarcoma, fibrosarcoma, and chordoma. Osteogenic and Ewing's sarcomas are the most common bone tumors of children.

Symptoms

• Bone pain  (may occur with or without movement and more intense at night)
• Cachexia
• Fever
• Impaired mobility (which may occur during late stages)
• May experience dull and usually localized pain
• May include a mass or tumor, which may be tender and may swell
• Pathologic fractures
• Weakness

Diagnostic tests 

A biopsy (by incision or aspiration) confirms primary malignant bone tumors. Bone X-rays and radio­isotope bone and computed tomography scans delineate the tumor size. A patient with sarcoma usually has elevated serum alkaline phosphatase levels.

Treatment

Treatment focuses on preserving the limb as well as controlling the cancer. Surgical resection of the tumor (often with preoperative radiation and postoperative chemotherapy) saves many limbs from amputation. Some facilities may perform both preoperative and postoperative radiation therapy and chemotherapy. or various other combinations.

Sometimes treatment calls for radical surgery. such as hemipelvectomy. When any type of surgical amputation is indicated, a 3" to 4" (8- to 10-cm) margin of healthy tissue should be left.

Intensive chemotherapy combines cyclophosphamide, cisplatin, vincristine, doxorubicin, and dacarbazine. Chemotherapy may be performed intraarterially into the long bones of the legs.