Malignant bone tumors account for approximately 5 percent of all childhood cancers. Fifty-six percent of all bone tumors diagnosed are osteosarcoma, most of which occur during the adolescent growth spurt. Males are affected more than females, and more black children are diagnosed than are white children.

Description

Osteosarcoma is a primary malignant cancer of the bone. It typically occurs at the ends of the long bones, usually at the knee. Other, less common sites are the upper arm (close to the shoulder), the pelvis, and the skull.

Treatment

During the last 25 years, treatment for osteosarcoma has greatly improved. Today, the majority of young patients with a primary tumor in a limb and no metastases will survive. Advances in surgical techniques have also markedly improved the quality of life for survivors.

When osteosarcoma is diagnosed in a bone, more tests are done to determine if the cancer has spread to other parts of the body. A biopsy is required to determine the type and stage of the tumor. Imaging studies that may be performed to check for metastases are magnetic resonance imaging (MRI), computed tomography (CT) of the chest, a bone scan, and sometimes a positron emission tomography (PET) scan.

There are two stages for osteosarcoma at diagnosis:

• Localized.  Tumors limited to the bone of origin.

• Metastatic.  Tumors found in other parts of the body, including the lungs, other bones, or distant sites.

Surgery

Surgery usually is performed after a period of chemotherapy. Successful surgical removal of the primary tumor most often consists of either limb-salvage surgery, rotationplasty, or amputation. A surgical procedure called a thoracotomy (i.e., opening the chest cavity) also is used when adolescents have metastases to the lungs.

Total removal of both gross and microscopic tumors is required to prevent recurrence. Factors that determine the choice of amputation or salvage therapy are tumor location, tumor size, presence of distant metastases, skeletal development, and patient preference. Whether or not the affected bone is broken at the time of diagnosis also affects the choice of treatment.

In up to 20 percent of osteosarcoma cases, areas of tumor develop inches away from the primary tumor. These areas, called skip lesions, can cause local recurrence in stumps after amputation. Prior to advances in CT and MRI techniques and radionuclide scanning, some surgeons removed the entire affected bone, resulting in disability and loss of function. Now, however, a variety of methods are used to salvage limbs. Bones from cadavers (called allografts) or pieces of the patient’s own bone (i.e., fibula or iliac crest) are used. Devices made from cobalt, chrome, or steel can be custom designed to replace the diseased bone. In some cases, the bone is removed and not replaced.

Radiation

Osteosarcoma usually does not respond well to radiation. Because of the risk of recurrence for tumors treated with radiation, it is used only in treating patients whose tumors cannot be completely removed surgically.

Chemotherapy

Chemotherapy is resumed after surgery has removed as much of the tumor as possible. A combination of some of the following drugs is used to treat osteosarcoma: doxorubicin (Adriamycin ^® ), high-dose methotrexate, cisplatin (Platinol ^® ), and cyclophosphamide (Cytoxan ^® ). Ifosfamide (Ifex ^® ), and/or etoposide, are sometimes used for children who relapse.

Late effects

This section briefly outlines some common and uncommon late effects from treatment. Remember that you may develop none, one, or several of these problems in the months or years after treatment ends.

Physical impairments. One of the universal late effects from treatment for osteosarcoma is coping with physical impairments from amputation or limb-salvage therapy. After limb-salvage therapy or fitting with a state-of-the-art prosthesis, many survivors are able to resume an active lifestyle, while others struggle to regain mobility. For more information, see Chapter 17 .

Heart problems. Heart problems can occur months or years after treatment with anthracyclines (i.e., doxorubicin, idarubicin, or daunorubicin), high-dose cyclophosphamide, or chest radiation. Symptoms include shortness of breath, fatigue, wheezing, anxiety, poor exercise tolerance, rapid heartbeat, and irregular heartbeat. The number of survivors who develop this late effect is small, but regular checkups are crucial. Survivors often have no symptoms, but problems may be found on cardiac tests such as echocardiograms, electrocardiograms (EKGs), and Holter monitors. For more information, see Chapter 12 .

Hepatitis C. Infection with the hepatitis C virus can develop in survivors who had blood transfusions prior to July 1992. For more information, see Chapter 15 .

Hearing loss. Cisplatin can result in mild to profound hearing loss in some children and teens. For more information, see Chapter 10 .

Learning disabilities. Treatment with high-dose methotrexate may result in cognitive problems. Learning disabilities can develop months or years after treatment ends. Typically, problems develop in the areas of mathematics, spatial relationships, problem solving, organization, planning, attention span, concentration skills, and social skills. For more information, see Chapter 8 .

Fertility. Female fertility usually is not affected by treatment for osteosarcoma unless the girl has very high doses of cyclophosphamide (more than 7.5 grams per square meter [grams/m ² ]) or ifosfamide (more than 60 grams/m ² ). In the majority of cases, girls treated for osteosarcoma have normal growth, sexual development, and fertility. The chances of having a normal pregnancy and birth are the same as in the general population.

Cyclophosphamide can cause a rapid decrease in sperm count in male teens who have passed puberty. Normal sperm production and motility generally return after treatment. After osteosarcoma treatment, younger males usually experience a normal puberty. However, young men who received very high doses of cyclophosphamide—more than 7.5 grams/m ² ) should have testosterone levels and sperm count checked. For more information about growth and fertility, see Chapter 9 .

Second cancers. A rare side effect from treatment of osteosarcoma is developing second cancers. For more information, see Chapter 19 .