Multivariate Assessment of Tumor Angiogenesis as a Prognostic Factor for Survival in Patients with Oligodendroglioma and Anaplastic Oligodendroglioma

Purpose/Objective(s): 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 assessmentofmolecular, pathological, and radiological parameters,we furtherassessedthe influenceoftumor angiogenesis on tumor progression and patient survival. Materials/Methods:PatientswithadiagnosisofODG,consecutivelytreatedin asingleinstitution,werereviewedandreclassified 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), absenceofseizure(p\0.001),vascularization(p=0.021),andage .55years(p=0.002).Asubsetofpatientswithtumornecrosis, increased vascularization, and absenceofseizures had a worse outcome than predicted,with a mediansurvival of14.2 months.The VEGF expression was significantly higher in this subgroup and correlated with tumor progression regardless of tumor grade. Conclusions:Based on the presenceof radiological or pathological necrosis, contrast enhancement or endothelialhyperplasia, 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.