Osteosarcoma (Osteogenic Sarcoma)
X-ray showing osteosarcoma in a patient's knee
X-ray showing knee with allograft after the osteosarcoma was removed
The most common primary malignant lesion of bone identified by its ability to form bone or bone tissue. There are a few different types of osteosarcoma which behave differently due to their biological makeup. Central osteosarcoma is the classical form usually occurring in adolescents located at the proximal or distal ends of long bones. These sarcomas are rated from low grade to high grade, with low grade being far less aggressive. Juxtacortical (both parosteal and periosteal) are usually considered low grade sarcomas. Telangiectatic osteosarcoma is rare, high grade and behaves as aggressively as classical osteosarcoma.
Osteosarcomas can occur in patients with other skeletal diseases such as Paget's disease, in bone previously treated with radiation for another type of tumor, or in any bone within a radiation field. Osteosarcoma incidence peaks in two age groups: 10-20 years and 50-60 (the older age group is often related to the patient with Paget's disease or those who received radiation). It is more common in males and occurs in areas of rapid growth. The most common site is the distal femur, proximal tibia, proximal humerus and proximal femur, although any bone may be involved.
The tumor is usually noted after trauma brings attention to a painful mass. Patients present with pain, local tenderness, a bony hard mass and decreased function of the body part. If the lesion has been untreated for a long period of time the patient may have symptoms of weight loss, fever, chills, lack of appetite and severe night pain not relieved by aspirin. Sometimes there is an increase in the blood level of alkaline phosphatase. X-rays show a destructive lesion as well as bone formation, a classical 'sun burst' streaming pattern. The outcome of patients without metastases at diagnosis is now quite good due to chemotherapy. Some patients have metastases at diagnosis, usually the lungs but may be in other bones, which worsens the prognosis.
Treatment for osteosarcoma involves chemotherapy and surgery. Chemotherapy is given before and after the surgical procedure in an attempt to reduce the size of the tumor making resection easier, and prevent the spread of cancer cells to other sites of the body. The chemotherapy protocol takes almost one year in total to complete. Previously, amputation was the only surgical treatment option to remove the tumor. Now there are limb-saving procedures which involve resection of the entire tumor as well as a margin of normal tissue (usually muscle and bone) around the lesion with replacement and reconstruction using an allograft (cadaver donor bone) or metal prosthesis. Adequate bone healing can take nine months to one year.
Rehabilitation requires casting for a few months followed by bracing and crutches (for lower extremity tumors) for almost one year. Physical therapy is necessary to regain motion and strength, but the progression is slow. It is important to realize that the affected limb will not look the same nor return to normal function. Patients return to normal daily routines but there are restrictions on physical activities. Prolonged walking, sitting, running, and heavy lifting should be avoided with lower extremity allografts. With upper extremity allografts, heavy lifting, pushing/pulling objects and repetitive use of the arm should be avoided. Patients with upper or lower extremity allografts should avoid contact sports.
Sometimes amputation may be the only surgical option due to the tumor size, location and/or invasion of surrounding vessels. Amputation insures complete removal of the tumor, and in most cases, the patient rapidly returns to a functional level. Final prosthetic fittings begin within one month after surgery if the residual limb (stump) is healed. Unlike the allograft patient, the functional limitations of the amputee are left to the imagination and determination of the patient.
If local recurrence or distant metastases occur, the combination of chemotherapy drugs is changed and surgical resection and radiotherapy is considered which involves intermittent periods of hospitalization.