Prognosticating metastatic osteosarcoma treated with uniform chemotherapy protocol without high dose methotrexate and delayed metastasectomy: a single center experience of 102 patients

Abstract

Purpose Data on prognostic factors in patients with metastatic osteosarcoma treated with a uniform chemotherapy protocol are limited. This study aimed to analyze demographic data, treatment outcomes, and prognostic factors in patients with metastatic osteosarcoma treated at a single institution using a standardized chemotherapy regimen excluding high-dose methotrexate. Methods A retrospective review was conducted on patients treated between June 2003 and December 2012. All patients received neoadjuvant chemotherapy, followed by local site surgery and metastasectomy at the completion of adjuvant chemotherapy. This single-institutional analysis focused on identifying factors associated with treatment outcomes. Results A total of 102 patients with metastatic osteosarcoma were included, with a median age of 18 years (range: 8–48 years) and a male-to-female ratio of 3.3:1. The median duration of symptoms was 4 months. Event-free survival (EFS) and overall survival (OS) at 5 years were 12.7 ± 0.1% and 28.1 ± 0.1%, respectively. On multivariate analysis, elevated serum alkaline phosphatase (p < 0.001) and >3 metastatic lesions (p = 0.04) were significantly associated with poorer EFS. Additionally, elevated serum alkaline phosphatase (p = 0.01), >3 metastatic lesions (p = 0.05), and marrow positivity (p < 0.001) were predictors of poorer OS. Conclusions This study presents the largest dataset to date on metastatic osteosarcoma treated using a uniform chemotherapy protocol without high-dose methotrexate. The identified prognostic factors—including elevated serum alkaline phosphatase and having more than three metastatic lesions—are consistent with previous findings. Notably, marrow involvement was a strong predictor of poor outcome. The results support a treatment approach that delays metastasectomy until the completion of chemotherapy, performing it concurrently with local site surgery.