Role of vascular endothelial growth factor as a tumour marker in osteosarcoma: a prospective study. A prospective study was undertaken to evaluate the diagnostic and prognostic significance of serum levels of vascular endothelial growth factor (VEGF) in patients with primary localised osteosarcoma.Serum VEGF levels were measured by an enzyme-linked immunosorbent assay (ELISA) in blood samples collected prechemotherapy, postchemotherapy, and postsurgery in 40 patients with histologically proven primary osteosarcoma. Comparison was made between serum VEGF level of healthy controls (n = 10) and prechemotherapy patient sera to evaluate its diagnostic potential. Serum VEGF levels of patients with and without metastasis were compared. Immunohistochemical staining was done to establish the correlation between serum and tissue VEGF expression. The Kaplan-Meier curve was used for survival analysisNo significant relationship was observed between serum VEGF levels and age, gender, tumour size, local recurrence or histopathological subtypes of osteosarcoma. We observed significantly raised mean serum VEGF in patient sera compared with healthy controls (p = 0.001). Significant fall in mean serum VEGF level was observed following chemotherapy (p = 0.001). Patients who developed metastases had significantly higher serum VEGF levels compared with the nonmetastatic group (P = 0.001). Serum VEGF levels correlated well with VEGF expression in tissues.Serum VEGF levels might prove to be of diagnostic, predictive and prognostic value in patients with primary osteosarcoma, although further studies with larger sample size and longer follow-up is needed to support the hypothesis.