Outcomes and survival rates of childhood osteosarcoma in Iran, A report from MAHAK Pediatric Cancer Treatment and Research Center, from 2007 to 2020.

Background: Osteosarcoma is one of the most common childhood bone malignancies. Although chemotherapy protocol including methotrexate is an effective treatment for osteosarcoma, some other regimens have excluded it because of its complications.

Methods: This retrospective study was conducted on 93 children younger than 15 years old who were diagnosed with osteosarcomafrom March 2007 to January 2020. Two chemotherapy protocols were administrated for patients, namely, DCM protocol (Doxorubicin-Cisplatin-Methotrexate) and German protocol (excluding methotrexate). All statistical analysis was conducted using SPSS-25 software.

Results: Among patients, 47.31% were male. Patients' age ranged from 3 to 15 with the mean of 10.41 ± 0.32 years. Femur was the most frequent primary tumor site (59.14%), followed by tibia (22.58%). Metastasis rate at diagnosis was 17.20% in our study. Furthermore, the 5-year overall survival (OS) of total patients was 37.3 ± 7.5%, whereas the 5-year OS of males and females was 33.6 ± 10.9% and 39.8 ± 10.6%, respectively. The 5-year OS of methotrexate regimen was 15.6 ± 9.6%, whereas that of methotrexate-free protocol was 50.2 ± 9.0%.

Conclusions: Female patients had better survival rates than males. In addition, the chemotherapy protocol excluding methotrexate significantly increased the overall and event free survival of patients.