Difference in pre- and postchemotherapy vascular endothelial growth factor levels as a prognostic indicator in osteosarcoma. This retrospective analysis examined the difference in pre- and postchemotherapy levels of vascular endothelial growth factor (VEGF) as an indicator of osteosarcoma prognosis. VEGF protein levels were assessed immunohistochemically in primary tumour samples from 61 osteosarcoma patients diagnosed between February 2001 and July 2005. The difference in pre- and postchemotherapy VEGF protein reduction levels was categorized into weak (23 patients) and strong (38 patients). The 5-year survival rate was significantly lower in the weak VEGF reduction group (34.8%) than in the strong VEGF reduction group (73.7%). The weak VEGF reduction group had significantly higher rates of metastasis and recurrence. Multivariate analysis confirmed that the change in VEGF was an independent and significant factor for predicting a good prognosis. The analysis of VEGF will enable clinicians to tailor surgery and chemotherapy regimens more appropriately, earlier in the disease process.