Developing a prognostic model for patients with localized osteosarcoma treated with uniform chemotherapy protocol without high dose methotrexate: A single-center experience of 237 patients.

Background: Studies of baseline prognostic factors in patients with localized osteosarcoma treated without high dose methotrexate are limited.

Methods: This is single-institutional review of localized osteosarcoma patients treated without high dose methotrexate between June 2003-December 2012. A multivariate analysis of impact of baseline and treatment characteristics on outcome was performed and a prognostic model was developed based solely on baseline factors for predicting event-free survival (EFS) and overall survival (OS).

Results: Of 237 patients with median age of 17 years (range 2-66 yrs), neoadjuvant chemotherapy (NACT) was administered in 220 (92.82%) patients. Post NACT, 200/237 (84.38%) patients underwent surgery. At 30 months median follow-up, 5-year EFS and OS were 36.60 ± 0.03%, and 50.33 ± 0.04%, respectively. In multivariate analysis, baseline factors including duration of symptom >4 months (P < 0.001) and good performance status (PS) (P < 0.001) predicted better EFS whereas good PS (P = 0.01) and normal serum alkaline phosphatase (SAP) (P = 0.03) predicted better OS. The 5-year EFS without any risk factor (symptom duration <4 months, PS>1) was 58.7 ± 0.1%, with either one factor 31.5 ± 0.1% and with both factors 21.9 ± 0.1%. The 5-year OS without any risk factor (PS>1, elevated SAP) was 66.9 ± 0.1%, with either one factor 57.9 ± 0.1% and with both factors 25.6 ± 0.1%.

Conclusions: This prognostic model assists in categorizing risk-groups within localized osteosarcoma.