First approach to treatment of osteogenic sarcoma is making a definitive diagnosis. After diagnosis has been established, patient should be put on preoperative adjuvant chemotherapy.
This should continue for four to six weeks. Advantgages of preoperative adjuvant chemotherapy are
- It reduces edema and decreases the size of the primary tumor thus making limb salvage surgery feasible
- It helps to determine the response of the primary tumor to a specific chemotherapeutic agents.
Early administration of chemotherapeutic agents,will destroy occult micrometastases and occult microextensions and will improve the overall prognosis.
After preoperative adjuvant chemotherapy, the next step is is definitive surgery followed by additional adjuvant chemotherapy for 12 months.
Tumor cell destruction as shown by histologic examination of the resected primary tumor helps in deciding chemotherapeutic agents.
There are four grades of tumour cell destruction.
- Grade I- Minimal or no effect
- Grade II- Partial response with 50 to 90 percent tumor necrosis.
- Grade III-Greater than 90 percent tumor necrosis, but definite foci of viable tumor are seen in some histologic sections.
- Grade IV- No viable tumor cells noted in any of the histologic sectioin.
In Grade I and II responses the chemotherapeutic agents are changed.
Parosteal osteogenic sarcoma and endosteal ostegenic sarcoma are low grade (Grade I) with less than 10 percent metastatic potential.
Classic osteosarcoma, radiation osteogenic sarcoma, and osteogenic sarcoma developing in Paget’s disease are high grade (Grade II), having a greater than 10 percent metastatic potential.
The part involved by osteogenic sarcoma should be ablated. However, whether the operative local control of the malignant tissue should be by wide local resection or by amputation of the limb-wide resection by transmedullary ablation or radical resection by disarticulation is controversial.
Before surgical ablation of the primary tumor it is essential to rule out the presence of metastases.
Osteogenic sarcoma spreads to the lungs early. In addition to conventional radiography, linear tomographic and computed tomographic studies of the chest and scintigraphic studies should be performed.
Limb Salvage Therapy
This course of action is based on the principle that a part of a limb that can be used should be preserved, provided it does not adversely affect survival.
Surgical adjuvant chemotherapy has made limb salvage feasible when diagnosis is made early, the tumor is intracompartmental, and neurovascular structures are not involved.
The objective of limb salvage is to preserve and to provide maximal function.
The drawbacks of limb salvage are-
- The preserved limb may be disfigured.
- Increased risk of local recurrence.
- Skip lesions may be missed.
Amputation
The level of amputation is determined by close scrutiny of
- The conventional radiographs
- Bone imaging with technetium-99m and gallium-67 citrate
- Linear and computed tomography
- Nuclear magnetic resonance imaging.
These surgical staging studies should be performed immediately prior to definitive surgery.
The patient and the parents need psychologic support. Initially there will be emotional resistance to ablation of a limb.
It is vital that these patients see other children with amputations and prostheses during the four to six weeks of preoperative adjuvant chemotherapy.
If pulmonary metastasis has already taken place at the time of initial diagnosis, the decision whether to amputate depends on amount of disability of the affected limb caused by local pain and tremendous size of the tumor, which may be so large and painful that the only means of controlling the misery is amputation. Other factors in making the decision are the general condition of the patient and his immediate prognosis.
If pulmonary metatases develop after amputation while adjuvant chemotherapy is in progress, the drugs may have to be changed. When a metatastic lesion is solitary, and sometimes when a maximum of only two or three foci of metastasis are present and remain stationary, a thoracotomy and wide excision are performed.
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