Diversity of angiogenesis among malignant bone tumors

Several studies have demonstrated that angiogenesis assessed by microvessel density (MVD) correlates with patient prognosis in various types of cancer, whereas data regarding the relevance of angiogenesis and prognosis in malignant bone tumors are scarce and controversial. The aim of this study was to examine MVD in representative malignant bone tumors, such as osteosarcoma, chondrosarcoma and Ewing's sarcoma, in order to clarify the role of angiogenesis in prognosis. A total of 69 patients with malignant bone tumors, including 44 osteosarcomas, 20 chondrosarcomas and 5 Ewing's sarcomas, were reviewed retrospectively and treated at our hospital between 1980 and 2007. Biopsy or pre-chemotherapy surgical specimens were immunohistochemically stained with anti-CD34 antibody. The MVD values of osteosarcomas and Ewing's sarcomas were significantly higher compared to chondrosarcoma. In osteosarcomas with high MVD, American Joint Committee on Cancer stage IIA, good histological response to chemotherapy was significantly correlated with better disease-free survival, while MVD was closely associated with age and chemotherapy response. In chondrosarcomas, the surgical margin (marginal and intralesional), MVD (high), tumor size (≥8) and histological grade (grades 2 and 3) significantly correlated with a shorter disease-free survival, while MVD was closely associated with age and histological grade. These findings showed that osteosarcomas and Ewing's sarcomas were hypervascular, compared to chondrosarcomas. In osteosarcomas, hypervascularity induced good chemotherapy response, leading to better prognosis, while in chondrosarcomas, high MVD was associated with histological grade and predicted poor prognosis.