Osteosarcoma in children

Osteosarcoma is a high-grade primary bone tumor consisting of spindle-shaped cells and characterized by the formation of an osteoid or immature bone tissue.

[1], [2]

Epidemiology of osteosarcoma

The incidence of osteosarcoma is 2.1 per 1,000,000 population per year. The age peak of the incidence falls on 10-19 years. In the older age, osteosarcoma usually occurs on a premorbid background (Paget's disease, previous bone irradiation, multiple exostoses, fibrous bone dysplasia).

The most frequent localization of osteosarcoma (up to 90% of cases) is long tubular bones. Bones that form the knee joint are affected in 50% of cases, the proximal end of the humerus - in 25%.

[3], [4], [5], [6], [7]

Diagnosis of osteosarcoma

In half of cases of osteosarcoma, an increase in the activity of alkaline phosphatase in the blood plasma was noted, but this symptom is non-specific, as it is found in many bone diseases.

Locally, a tumor of dense consistency is associated with the bone. Pain is the most frequent complaint of patients with osteosarcoma. In adjoining joints, as a rule, effusions are not detected, movements are preserved. Pathological fractures occur in less than 1% of cases. Systemic symptoms are also rare.

[8], [9], [10], [11]

Radiography

The most common radiographic signs of bone tumors are foci of osteolysis or pathological (tumor) osteogenesis. Often observe a mixed picture with the predominance of a component. The most complex in the diagnostic plan is the osteolytic type of bone changes. In this case, osteosarcoma must be differentiated from fibrosarcoma, bone cysts, giant cell tumor. Tumor osteogenesis is one of the reliable signs of osteosarcoma.

Radiographic evaluation of bone tumors is carried out according to the following parameters.

• Localization of osteosarcoma. According to the field theory, tumors from spindle-shaped cells (including osteosarcoma) are localized mainly in the metaphysis of long tubular bones, while tumors from round small cells (Ewing's sarcoma, non-Hodgkin's lymphomas) are in the diaphysis area.
• Limits of osteosarcoma. Reflect the growth rate and the reaction of surrounding tissues. Malignant and aggressive benign tumors are characterized by fuzzy boundaries or their absence.
• Destruction of bones. This sign is a reliable symptom of a bone tumor. The most pronounced bone destruction is detected with high-quality malignancies. It serves as a marker of tumor activity.
• Condition of bone matrix (pathological osteogenesis). Areas of increased density may be due to the presence of calcifications, lesions of sclerosis or newly formed bone tissue.
• Reaction of the periosteum. Benign tumors, as a rule, do not cause destruction of the periosteum. Malignant tumors of bones, on the contrary. Characterized by the presence of a pronounced periosteal reaction with a wide transition zone and the involvement of soft tissues in the process.

An important role in assessing the prevalence of tumors is played by scintigraphic examination of bones. The relationship between the tumor and surrounding tissues is assessed by angiography and MRI.

Treatment of osteosarcoma in children

Until the early 1980s, the generally accepted tactic of treating a localized form of osteosarcoma was amputation of the limb to an upper joint, with respect to the affected bone. Organ-preserving operations became possible due to the introduction of chemotherapy and the improvement of orthopedic technology. Currently, such operations are performed by most patients with osteosarcoma, the results of treatment do not deteriorate. A necessary condition for carrying out organ-saving operations is the possibility of resection of the tumor within the limits of healthy tissues with the subsequent restoration of limb functions. Be sure to take into account the patient's desire for the type of operation.

The size of the operation determines the localization and size of the tumor. For a qualitative implementation of the surgical stage of treatment, a clear imaging of the focus is extremely important. The volume of removal and long-term consequences of the operation largely depend on the involvement of neuromuscular bundles in the tumor process. For their accurate visualization, preoperative angiography is advisable. The defeat of the tumor of the main vessels and nerves, as well as extensive involvement of surrounding tissues or their contamination by tumor cells, determined by biopsy, is a contraindication to organ preservation operations.

Chemotherapy has made a significant contribution to improving the results of treatment of osteosarcoma. The most effective drugs are doxorubicin, cisplatin, ifosfamide and methotrexate in a high dose. The main goal of postoperative chemotherapy is to achieve local tumor control.

Osteosarcoma is a tumor that is insensitive to radioactive radiation. The antitumor effect is achieved only by doses, leading to severe and irreversible side effects. At present, irradiation is used with a palliative purpose for non-detectable tumors (osteosarcoma of the axial skeleton, bones of the facial skull) and in the presence of bone metastases.