Today's standard treatment with radiotherapy and temozolomide yields a life expectancy of 1.5-3 years in patients with high-grade astrocytomas. Thus, there is a need for further therapeutic improvements in this patient population. The purpose of the current trial is to explore whether radiotherapy and temozolomide affect the tumor vasculature in patients with high-grade astrocytomas. If vascular effects are identified, future clinical trials can be proposed wherein anti-angiogenic agents are added to increase patient survival. Additionally, stem cells within malignant brain tumors is an important new area of research in this patient population, and investigations herein could contribute to identify new predictive markers and therapeutic targets.~Primary objective: To assess the vascular perfusion and permeability characteristics of high-grade astrocytomas (anaplastic astrocytoma and glioblastoma multiforme) using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in patients receiving radiotherapy and temozolomide. Furthermore to assess whether therapy-induced changes in tumor perfusion is correlated with progression-free survival.~Secondary objectives:~Analyze circulating endothelial cells in the blood by flow cytometry to explore whether these cells can be used as an indirect estimate of angiogenesis in high-grade astrocytomas~Analyze tumor specimens from patients that have had their gliomas debulked before commencing therapy~immunostaining of the tumor vasculature to assess microvessel density~immunostaining for tumor stem cells~flow cytometric assessment of dissolved tumor tissue to look for tumor stem cells~Assess progression-free survival of all patients included in the study, in order to correlate the survival data with the above tissue sampling results.
The purpose of the current trial is to explore whether the standard treatment with radiotherapy and temozolomide affect the tumor vasculature in patients with high-grade astrocytomas. If vascular effects are identified, future clinical trials can be proposed wherein anti-angiogenic agents are added to increase patient survival.