A study of 28 flat bone osteosarcomas: prognostic factors and early and long-term outcome.

Limited information is available on clinical management of Flat Bone Osteosarcomas (FBOS). We retrospectively analysed prognostic factors and outcome. Twenty-eight patients were treated in our institution. Survival curves were obtained by the Kaplan-Meier method and compared with the log-rank test. The overall survival (OS) rates at 5 and 10 years were 52.4% and 45.8% respectively. The event-free survival (EFS) rates at 5 and 10 years were 41.5%. The factors influencing EFS in univariate analysis were location, metastatic disease at diagnosis, effect of neoadjuvant chemotherapy, histological response and adequate local tumour control. Location, metastatic disease at diagnosis, effect of neoadjuvant chemotherapy, histological response and local recurrence were statistically correlated with OS. Multivariate analysis retained metastatic disease at diagnosis as prognostic factors of EFS and OS. Our results suggest a more favourable outcome of FBOS as the use of a treatment scheme based on the protocols for long bone osteosarcomas. However, an adequate local treatment is essential to ensure a better outcome.