Osteosarcoma in children aged less than five years at diagnosis: Experience of the Cooperative Osteosarcoma Study Group

Abstract

9554 Background: The incidence of osteosarcoma considerably varies with age and preschool children are reported to be extremely rarely affected. This study was conducted to investigate presentation, treatment, and outcome in very young children with osteosarcoma. Patients and Methods: The authors retrospectively analyzed the collected data of 2,706 consecutive patients with newly diagnosed high-grade osteosacroma of bone registered in the COSS studies between 1976 and 2005; and identified 28 patients (1%) aged less than five years at diagnosis. Demographic, diagnostic, tumor, and treatment related variables; response and survival data of these 28 patients were analyzed. Results: Of the 28 (male, N = 16; female, N = 12) identified toddlers (two years, N = 4; three years, N = 10; four years, N = 14), 27 presented with a high-grade central osteosarcoma of an extremity (femur, N = 12; humerus, N = 10; tibia, N = 5) and one with a secondary osteosarcoma of the orbit. The size of the primary extremity tumor was large in 74% of patients. Primary metastases were detected in 4/28 children. All 28 patients received multiagent chemotherapy, and 13 of the 21 analyzed tumors responded well to neoadjuvant chemotherapy (>90% necrosis). Limb sparing surgery was feasible in 11 children, whereas ablative procedures were performed in 14 patients. A macroscopically complete surgical remission of all clinically detectable tumors was achieved in 24/28 patients during front line therapy. With a median follow-up of 1.7 years (4.2 years for survivors), 15/28 patients were alive. Outcome was poorer for the 28 toddlers compared to the 2,678 older patients (5-year event free survival 43% ± 10% vs. 56% ± 1%)(P = 0.02). Conclusion: Osteosarcoma is extremely rare in preschool children. These young patients often have large tumors which may require mutilating resections. Despite the high rate of ablative surgery, the prognosis, however, may be poorer compared to older patients. No significant financial relationships to disclose.