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Angiogenesis is a major hallmark of cancer cells, and glioblastomas are among the most angiogenic tumors. The cascade of angiogenesis is probably initiated by hypoxia, leading to the production of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF). Both VEGF and bFGF have paracrine effects on endothelial cells, pericytes, or both, causing the formation of hyperpermeable tumor blood vessels. Advanced MRI techniques, such as dynamic contrast-enhanced, dynamic susceptibility, and arterial spin labeling MRI, have provided semiquantitative measurements of tumor vascular permeability and perfusion. A decrease in vascular permeability and perfusion can be detected after antiangiogenesis drug treatment, either with monoclonal antibody such as bevacizumab that sequesters VEGF, or small-molecule VEGF receptor tyrosine kinase inhibitors. Therefore, antiangiogenesis therapies are being increasingly adopted for treating glioblastomas. However, caution must be exercised because neural stem cells are also sensitive to antiangiogenesis drugs and the combined effect of ionizing radiation. This article summarizes 30 years of laboratory and clinical research on glioblastoma angiogenesis and discusses its underlying biology, clinical trial results, vascular neuroimaging, and the potential side effects of antiangiogenesis treatment.

Malignant gliomas are among the most devastating human cancers. The infiltrating nature of these malignancies makes complete surgical resection nearly impossible. Conventional therapy for malignant gliomas consists primarily of surgical debulking followed by radiation therapy and possibly chemotherapy. The major factor limiting intracranial therapeutic levels of systemically administered chemotherapeutics is the physiologic barriers of the brain. This has led to the development of novel methods of drug delivery such as implantable polymers containing chemotherapeutic agents. Several phase III clinical trials show that implantation of carmustine-containing biodegradable polymers prolongs survival in patients with both recurrent and newly diagnosed malignant gliomas. In this article, we summarize these trials and discuss ongoing clinical trials involving implantable chemotherapy-containing polymers in the treatment of patients with malignant gliomas.

Brain metastases are an increasingly important determinant of survival and quality of life in patients with cancer. Current approaches to the management of brain metastases are driven by prognostic factors, including the Karnofsky Performance Status, tumor histology, number of metastases, patient age, and status of systemic disease. Most brain metastases are treated with radiosurgery, computer-assisted surgery, or whole brain radiation therapy. Remarkable advances in computer-assisted neuronavigation have made neurosurgical removal of metastases safer, even in eloquent areas of the brain. Computerization also enhances the efficacy and safety of conformal radiosurgery planning using various modern stereotactic radiosurgery (SRS) technologies, including newer frameless-based systems. Controversial issues include whether to defer whole brain radiotherapy (WBRT) in patients undergoing SRS or image-guided surgery and when to use SRS “boost” in a patient undergoing WBRT. The determination of how best to apply these treatments for individual patients cannot be standardized to a single paradigm, but data from well-controlled studies help physicians make informed decisions about the benefits and risks of each approach.

The FDA's approval of bevacizumab for recurrent glioblastoma on May 9, 2009, was based on the significant response rate and clinical benefits seen from randomized phase II studies. Large-scale phase III data are unavailable. In an effort to determine benchmark efficacy parameters for bevacizumab and analyze its dose–response effect, the authors performed a meta-analysis of 15 studies published from 2005 to 2009, involving 548 patients with a median age of 53 years (range, 5–74 years), that used bevacizumab to treat recurrent glioblastoma. Median overall survival was 9.3 months (95% CI, 7.9–10.6 months). The respective 6-month progression-free and 6-month overall survival rates were 45% (95% CI, 34%–57%) and 76% (95% CI, 69%–84%), respectively. Median time to tumor progression was 6.1 months (95% CI, 4.2–8.1 months). The response analysis yielded a 6% complete response (95% CI, 2%–9%), 49% partial response (95% CI, 37%–61%), and 29% stable disease (95% CI, 20%–38%). No difference was seen in bevacizumab dose–response benefit between 5 mg/kg and 10 to 15 mg/kg. The efficacy benchmarks from this meta-analysis did not differ from those of the recently published randomized phase II studies. The lack of a dose–response effect would require confirmation in a prospectively conducted clinical trial.

The NCCN Guidelines for Central Nervous System (CNS) Cancers focus on management of adult CNS cancers ranging from noninvasive and surgically curable pilocytic astrocytomas to metastatic brain disease. The involvement of an interdisciplinary team, including neurosurgeons, radiation therapists, oncologists, neurologists, and neuroradiologists, is a key factor in the appropriate management of CNS cancers. Integrated histopathologic and molecular characterization of brain tumors such as gliomas should be standard practice. This article describes NCCN Guidelines recommendations for WHO grade I, II, III, and IV gliomas. Treatment of brain metastases, the most common intracranial tumors in adults, is also described.

For many years, the diagnosis and classification of gliomas have been based on histology. Although studies including large populations of patients demonstrated the prognostic value of histologic phenotype, variability in outcomes within histologic groups limited the utility of this system. Nonetheless, histology was the only proven and widely accessible tool available at the time, thus it was used for clinical trial entry criteria, and therefore determined the recommended treatment options. Research to identify molecular changes that underlie glioma progression has led to the discovery of molecular features that have greater diagnostic and prognostic value than histology. Analyses of these molecular markers across populations from randomized clinical trials have shown that some of these markers are also predictive of response to specific types of treatment, which has prompted significant changes to the recommended treatment options for grade III (anaplastic) gliomas.

The NCCN Guidelines for Central Nervous System (CNS) Cancers focus on management of the following adult CNS cancers: glioma (WHO grade 1, WHO grade 2–3 oligodendroglioma [1p19q codeleted, IDH-mutant], WHO grade 2–4 IDH-mutant astrocytoma, WHO grade 4 glioblastoma), intracranial and spinal ependymomas, medulloblastoma, limited and extensive brain metastases, leptomeningeal metastases, non–AIDS-related primary CNS lymphomas, metastatic spine tumors, meningiomas, and primary spinal cord tumors. The information contained in the algorithms and principles of management sections in the NCCN Guidelines for CNS Cancers are designed to help clinicians navigate through the complex management of patients with CNS tumors. Several important principles guide surgical management and treatment with radiotherapy and systemic therapy for adults with brain tumors. The NCCN CNS Cancers Panel meets at least annually to review comments from reviewers within their institutions, examine relevant new data from publications and abstracts, and reevaluate and update their recommendations. These NCCN Guidelines Insights summarize the panel’s most recent recommendations regarding molecular profiling of gliomas.