Osteosarcoma (synonyms: chondroblastic sarcoma; chondroplastic osteosarcoma; fibroblastic osteosarcoma; fibroblastic sarcoma; juxtacortical osteosarcoma; small cell osteosarcoma; medullary osteosarcoma; osteoblastic sarcoma; osteogenic sarcoma; osteosarcoma in Paget’s disease of bone; parostal osteosarcoma; peripheral osteosarcoma; teleangiectatic osteosarcoma; ICD-10 C41. 9: Malignant neoplasm of bone and articular cartilage of other and unspecified locations) is a malignant (malignant) neoplasm (neoplasm) of bone (bone tumor). Characteristically, the cells of osteosarcoma form osteoid (soft, not yet mineralized ground substance (matrix) of bone tissue/”immature bone”).
Osteosarcoma is a primary bone tumor. Typical for primary tumors is their respective course and that they can be assigned to a certain age range (see “Frequency peak”) as well as a characteristic localization (see under “Symptoms – complaints”). They occur more frequently at the sites of most intensive longitudinal growth (metaepiphyseal/articular region). This explains why bone tumors occur more frequently during puberty.
The following forms of osteosarcoma are distinguished:
- Central (medullary) osteosarcoma – 80-90% of cases; located in the center of the bone.
- Superficial (peripheral) osteosarcoma – located in the area of the periosteum (bone skin).
For more information, see “Classification”.
Sex ratio: boys / men are more often affected than girls / women.
Frequency peak: osteosarcoma occurs predominantly between the 10th and 20th year of life. A second incidence peak is found between the ages of 40 and 60.
Malignant bone tumors account for 1% of all tumors in adults. Osteosarcoma is the most common primary malignant bone tumor (40%), followed by chondrosarcoma (20%) and Ewing’s sarcoma (8%).
The incidence (frequency of new cases) is 2-3 cases per 1,000,000 inhabitants per year (in Germany).
The course and prognosis depend on the location, size, extension and stage of the osteosarcoma. Patients with osteosarcoma of the trunk or with a large tumor have a less favorable prognosis than patients with osteosarcoma in an extremity or with a small tumor. Osteosarcoma grows rapidly and infiltrates (invades/displaces), meaning it crosses anatomic boundary layers such as adjacent structures, bone boundaries, and growth plates. It usually spreads rapidly to other areas of the skeleton and forms hematogenous (via the bloodstream) metastases early (after a few weeks/few months) – especially to the lungs, but also to the bones and liver. Consequently, the treatment for osteosarcoma is resection (surgical removal). Usually, neoadjuvant chemotherapy (NACT; chemotherapy before surgery) is given to shrink the tumor and kill any metastases (daughter tumors) that may be present. At the time of diagnosis, 20% of those affected already have metastases and probably another 60% have micrometastases. Following removal of the osteosarcoma, chemotherapy may be required again, depending on the situation (= adjuvant chemotherapy). The patient’s response to chemotherapy plays a decisive role with regard to prognosis.
The 5-year survival rate is between 50-70%. The survival rate is reduced if the sarcoma has already spread at the time of diagnosis (approx. 40 %). If recurrence (recurrence of the disease) occurs, the 5-year survival rate is less than 25%.
