Background: The incidence of osteosarcoma peaks in adolescence and is much lower in preadolescence. However, reports on its clinical features in preadolescent patients are conflicting. In this study, we attempted to assess the differences in clinical appearance and prognosis of the malignancy between preadolescent and adolescent patients.
Methods: Between January 1980 and January 2006, 13 preadolescent and 58 adolescent patients with high-grade osteosarcoma were treated at our institute, and their medical records were reviewed and compared.
Results: The sex distribution, primary metastasis rate, pathologic fracture, histologic type, primary tumor location, and percentage of high alkaline phosphatase level were not different between the 2 groups. Poor responders (tumor necrosis rate < 90%) were more common in the preadolescent group (80% vs. 43%, p = 0.035). Overall survival rates in the preadolescent and adolescent groups were 51.3% and 56.4%, respectively (p = 0.735). In patients without primary metastasis, the 5-year overall survival rates were 60.6% and 66.7% for 11 preadolescents and 39 adolescents, respectively (p = 0.925).
Conclusion: Considering the common findings in both groups, we suggest that preadolescent patients should be treated with the same regimen as that used for adolescent patients.