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Osteogenic sarcoma (osteosarcoma) is a cancer that starts in the bone. It often starts in the ends of the bones where new bone tissue forms as a young person grows. Bones in the thigh, upper arm, and shin are the most common sites, but osteosarcoma can occur anywhere in the body. It usually develops during the period of rapid growth during adolescence, as a teenager matures into an adult.
Osteosarcoma is the most common malignant bone tumor in youth. The average age at diagnosis is 15 years. Boys and girls have a similar incidence of this tumor until late adolescence, at which time boys are more commonly affected.
The cause of osteosarcoma is unknown. Only rarely does osteosarcoma run in families. A defective tumor suppressor gene, allowing tumors to grow, has been linked to increased risk of this disease and is also associated with familial retinoblastoma, a childhood cancer of the eye. Children with familial retinoblastoma have a high risk for osteosarcoma in adolescence.
Pain in the affected bone is the most common symptom. This pain may initially come and go and then gradually become more severe and constant. As the tumor grows, there may be visible swelling and limitation of motion. Tumors in the legs cause limping, while those in the arms cause pain on lifting. Swelling over the tumor may be warm and slightly reddened.
Sometimes, the first sign may be a bone fracture. The tumor may cause weakness in the affected area of the bone. A fracture at the site of the tumor is called a “pathological fracture,” which occurs after what often seems like a routine movement. For example, a young athlete who breaks an arm during a routine throw should be tested to ensure there is no underlying bone problem, such as a tumor or cyst.
Osteosarcoma Diagnostic Tests
An X-ray will be taken, and if it suggests that there is a tumor, a CT (computerized tomography) or MRI (magnetic resonance imaging) scan of the bone will show the characteristics of the tumor. A biopsy is always necessary to identify the type of tumor. This should be done by an orthopedist with expertise in cancer surgery, to ensure that the biopsy is done in such a way that later surgical procedures are not affected. A bone scan, CT scan of the lungs, and blood tests will be administered to find out whether the cancer has spread.
Most children with osteosarcoma can be cured. Treatment will depend on a number of factors including the size, position, and stage of the tumor (how far the cancer has spread).
In general, chemotherapy (treatment with anticancer drugs) is given to shrink the main tumor. This is often given before the tumor is removed by surgery. Radiation therapy (treatment with targeted X-rays) is rarely needed but is occasionally used when the tumor cannot be removed by surgery.
Treatment usually lasts five to eight months.
The type and extent of surgery depends on the position and size of the tumor. Surgery may include removing the whole limb (amputation) or part of the affected bone, which is then replaced by some form of artificial limb (prosthesis). If only part of the affected bone is removed, this is known as limb-sparing surgery.
Amputation of the limb is sometimes unavoidable if the cancer is affecting the surrounding blood vessels and nerves. After amputation, an artificial limb will be fitted and will be regularly adjusted as the child grows. The artificial limb can function very well; it should be possible for the child to engage in with normal activities and even play sports.
Very young children will often need amputation because significan growth of a prosthesis is difficult to achieve.
Limb-sparing surgery preserves the limb. The bone may be replaced with a prosthesis (a specially-designed, artificial part), or with bone taken from another part of the body.
After this type of surgery, the child will usually be able to walk and run without the need for crutches or other supports. However, patients are advised not to participate in any contact sports because, if the bone graft or prosthesis is damaged, it could require another major operation to repair or replace it.
If the child is growing,the limb prosthesis will need to be lengthened as the bone grows. This will mean further short stays in the hospital.
Patients treated for osteosarcoma will have the area of the tumor examined radiographically, with X-rays and other imaging techniques, at three to six month intervals for three to five years. At the same time, CT (computerized tomography) scans of the lungs will be performed as early discovery of lung lesions (tumor cells that have spread to the lungs) allows for easier removal by surgery.
Drug therapy with doxorubicin (Adriamycin) can potentially affect the heart. Patients with osteosarcoma who have received this drug as part of their therapy will need to have echocardiograms and electrocardiograms performed at least every three years. Certain types of exercise are better for the survivor’s heart and should be discussed with the specialist as part of follow-up care.
In addition, the patient’s hearing should be checked within the year of completing therapy, and then three to five years later.
The orthopedic surgeon will schedule follow-up visits for years after surgery to ensure that the prosthesis is working well and to reinforce suggestions for exercise programs.