Osteosarcoma
Osteosarcoma is one of the two most common malignant bone tumors. The other one is Ewing’s sarcoma. In general, bone tumors accounted for 5.5% of all pediatric malignancies in the Philippines.
Osteosarcomas usually arise from the metaphyseal end of long bones of the limbs and in the bones of the pelvis. These are commonly seen in the second and third decades of life and have more preponderance to the male population in a ratio of 1.6:1 (M:F).
The four possible etiologic factors identified are the following:
1. Rapid bone growth around puberty
2. Radiation or radioactive injections
3. Pre-existing benign bone disorders
4. Trauma
Clinically, the tumor will present with local pain , tenderness, swelling and limping. Approximately 50-80% of osteosarcomas is present in the area around the knee and 9-15% in the proximal humerus. This tumor shows rapid growth with metastases within 2 years of the appearance of the primary tumor.
In xrays, this osteosarcomas will present as “sun-ray” about the periphery of the lesion. Other laboratories have to be taken during the work up.
Surgery , either amputation or endoprosthetic replacement of the femur and knee is done after a pre- operative chemotherapy. After the surgical procedure, the histologic response of the primary tumor to chemotherapy will be evaluated. A tumor necrosis of 90% is a good response and this indicates a good prognosis as the patient may survive 3 years or more.