Osteosarcoma: Cancer and Tumor

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Abstract
Osteosarcoma is a primary malignant tumor of bone that is characterized by the production of osteoid or immature bone by the malignant cells [8]. While it is a rare disease on the whole, it is one of the most common types of cancer in children and adolescents [3, 8]. Because it affects most patients during growth spurts in teen years, clinical presentations are many times diagnosed late due to parents and physicians attributing the pains to growing pains or athletic sprains [3]. Early detection and administration of chemotherapies lower the risk of metastasis and stage of the disease, which in turn make treatment less drastic and more effective [3,6, 7]. The prognosis and survival rate of patients has dramatically increased with the aid of chemotherapies and radiotherapies [6,7]. Osteosarcoma

Osteosarcoma is the most common type of primary bone cancer, and the fifth most common type of cancer in adolescents [3, 8]. It is a bone tumor that can occur in any bone, but most frequently occurs in the long bones of the arms and legs near the growth plates. The most common sites are distal femur, the proximal tibia, and the proximal humerus (See Figure 1). Other tumor locations are the skull or jaw and hip bones. At the time of diagnosis 15-20% of patients have detectable metastases that have spread to the lungs or other bones [7]. Unlike secondary bone cancers, it is one of the few that begins in the bones and sometimes metastasize to other parts of the body, usually the lungs or other bones [6]. In fact, the most common cause of mortality derived from osteosarcoma is caused by pulmonary metastatic disease [3](See Figure 2). It is believed that osteosarcoma arises from primitive mesenchymal bone-forming cells, or osteoblasts, and most commonly affects adolescents between the ages of 10 and 25, who are experiencing growth spurts [3, 6, 7]. Boys and girls have a similar incidence of this tumor until late adolescence, at which time boys (with a ratio of 1.25:1; M:F [2]) are more commonly affected [5]. Incidences are also slightly higher for blacks than white ethnicity [3]. Evidence shows that teens that are taller than average have an added risk for developing the disease [6]. Despite osteosarcoma being amongst one of the more common types of bone cancer in adolescence, it is a rare tumor, accounting for only 1 percent of all cancers diagnosed in the United States annually. Approximately 750 to 900 new cases are diagnosed each year in the U.S., of which 400 arise in children and adolescents younger than 20 years of age[8]. Presentation

The most common presenting symptoms of osteosarcoma are pain and swelling in the arm or leg, particularly with activity [3, 6]. Symptoms may be present for weeks or months before a patient is diagnosed due to parents attributing it to sprains or growth pains [3]. Pain may be worse at night and even awaken the patient from sleep. Pain during inactivity is a particular concern [4, 6]. Pathologic fractures are not particularly common. The exception is the telangiectatic type of osteosarcoma, which is more commonly associated with pathologic fractures (found in 25% of cases [2]) [3]. In this case a bone fracture may occur spontaneously after a minor bump [4]. There is often a history of trauma and in some cases patients the first sign of disease is a broken arm or leg due to weakening of the bone [3, 6]. Tumor spread to the lungs only rarely results in respiratory symptoms and usually indicates extensive lung involvement [3]. “Physical examination findings are usually limited to the site of the primary tumor, as follows: * Mass: A palpable mass may or may not be present. The mass may be tender and warm, although these signs are indistinguishable from osteomyelitis. Increased skin vascularity over the mass may be discernible. Pulsations or a bruit may be detectable. * Decreased range of motion: Involvement of a joint should be obvious on physical examination. *...
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