According to World Health Organization (WHO) and Daumas-Duport grading systems, progression of oligodendrogliomas (ODGs) to a higher grade (Group III, Grade B) is associated with increased angiogenesis. Based on multivariate assessment of molecular, pathological, and radiological parameters, we further assessed the influence of tumor angiogenesis on tumor progression and patient survival.
Materials/Methods
Patients with a diagnosis of ODG, consecutively treated in a single institution, were reviewed and reclassified according to WHO and Daumas-Duport grading systems. The MRI scans were reviewed to assess contrast enhancement and necrosis. Tissue sections were used for pathology review and to evaluate immunostaining of VEGF, VEGF-R, Ki-67, and CD34. Multivariate analysis was performed including demographic, pathological, and radiological data associated with tumor angiogenesis and patient survival.
Results
A total of 134 patients were analyzed from 1994-2000. This included patients with low-grade (WHO II, n = 47) and anaplastic ODG (WHO III, n = 87). Multivariate analysis identified four independent poor prognostic factors: necrosis (p = 0.001), absence of seizure (p < 0.001), vascularization (p = 0.021), and age >55 years (p = 0.002). A subset of patients with tumor necrosis, increased vascularization, and absence of seizures had a worse outcome than predicted, with a median survival of 14.2 months. The VEGF expression was significantly higher in this subgroup and correlated with tumor progression regardless of tumor grade.
Conclusions
Based on the presence of radiological or pathological necrosis, contrast enhancement or endothelial hyperplasia, and absence of seizures, a high-risk group of ODG can be identified with significantly worse overall survival. Also, VEGF over-expression in Grade II ODG constitutes an early marker for predicting tumor progression to a higher grade.
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