Increased vascularity is a pivotal event in tumor progression and has prognostic meaning in numerous cancers. Recently developed agents have been designed to target and inhibit angiogenesis factors, preventing the formation of new blood vessels that supply the tumor and allow cancer cells to survive and multiply.
Glioblastoma multiforme is the most aggressive and infiltrative type of brain tumor and it is supported by a large network of blood vessels that ultimately promote cell division and circulation. Because of its abnormal vascularity, this type of tumor has been treated with anti-angiogenic agents, however, there are no established biomarkers that can track treatment response or relapse.
Scientists from the University of Melbourne, Australia, were interested in this project and focused on the development of novel circulating and imaging biomarkers. The subjects of their study were both glioblastoma patients and healthy volunteers who underwent collection of blood samples and perfusion-weighted MRI (PWI) scans, an imaging technique performed to quantify cerebral blood flow and blood volume.
From contrast-enhancing regions on T1-weighted sequences, Analyze software was used to create tumor regions of interest (ROI). This information was then converted to perfusion-weighted MRI color maps that showed the areas of increased cerebral blood volume within the tumor. Relative cerebral blood volume (rCBV) values, the ratio between tumor cerebral blood volume and normal-appearing white matter, were then calculated.
The team showed that patients with higher levels of circulating endothelial progenitor cells, which are mobilized from the bone marrow in response to various angiogenic stimuli, also had increased tumor vascularity, determined by high rCBV values. Furthermore, the scientists were able to determine that the concentration of circulating endothelial cells, mature endothelial cells that detach and enter the bloodstream, were significantly higher in patients with the tumor than in the controls. These levels decreased noticeably postoperatively.
Findings from this study suggest that these parameters may potentially be considered useful biomarkers to monitor glioblastoma multiforme patients during treatment with anti-angiogenic agents.Brain Studies, Brain Tumor