Clinical Features, Prognostic Factors and Treatment Outcome of Chondroblastic Osteosarcoma: A Single-Center Experience

Objective: Chondroblastic osteosarcoma is an aggressive bone cancer with poor outcome accounting for 25% of cases of conventional osteosarcoma. The aim of our study was to assess the clinico-epidemiological profile, prognostic factors, and treatment outcome of chondroblastic osteosarcoma. Methods: A monocentric retrospective study was conducted between 1982 and 2020. Data of chondroblastic osteosarcoma patients treated in Salah Azaiz Institute were collected. Patient's treatment variables, prognostic factors and and treatment outcome were assessed. Results: Thirty patients were included. Most of them (n=24) were younger than 25 years. Femur (n=15) and tibia (n=8) were the most common sites involved. Twenty patients had localized disease and 10 patients had metastatic disease on presentation. Neoadjuvant chemotherapy was performed in 23 patients. They received combination regimen of methotrexate, adrimaycin and cisplatin (MAP) (44%), methotrexate, etoposide and ifosfamide (30%), combined doxorubicin-ifosfamide-cisplatin (API) and doxorubicinifosfamide (AI) (22%), etoposide, ifosfamide and cisplatin (VIP) (4%). 16% of patients had partial response, 63% a clinical progression and 21% patients a stable disease. Surgery was performed in 22 patients. Of 16 patients operated, 4 (25%) were good responders while 12 (75%) were poor responders. For patients with metastatic disease, only one achieved complete remission. Six patients progressed after treatment and two died. For patients with localized osteosarcoma, 6 patients had local recurrence and 6 patients had distant metastases. Median overall survival was 35 months. Overall survival at 2 years was 43%. Median disease free survival was 12 months. Disease free survival at 2 years was 21%. The absence of clinical response after neoadjuvant chemotherapy and age> 25 years were prognostic factor influencing disease-free-survival (p=0.025 and p=0.012, respectively). Conclusion: Chondroblastic osteosarcoma is an aggressive tumor with a tendency for local recurrence and distant metastasis. Younger onset age and response to neoadjuvant chemotherapy can predict better disease free survival.