Stereotactic Radiosurgery and Radiotherapy for Recurrent Glioblastoma
Stereotactic Radiosurgery and Radiotherapy for Recurrent Glioblastoma
Glioblastoma multiforme (GBM) is a devastating malignant brain tumor characterized by resistance to available therapeutic approaches and relentless malignant progression that includes widespread intracranial invasion, destruction of normal brain tissue, progressive disability, and death. Stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT) are increasingly used in patients with recurrent GBM to complement traditional treatments such as resection, conventional external beam radiotherapy, and chemotherapy. Both SRS and fSRT are powerful noninvasive therapeutic modalities well suited to treat focal neoplastic lesions through the delivery of precise, highdose radiation. Although no randomized clinical trials have been performed, a variety of retrospective studies have been focused on the use of SRS and fSRT for recurrent GBMs. In addition, state-of-the-art neuroimaging techniques, such as MR spectroscopic imaging, diffusion tensor tractography, and nuclear medicine imaging, have enhanced treatment planning methods leading to potentially improved clinical outcomes. In this paper the authors reviewed the current applications and efficacy of SRS and fSRT in the treatment of GBM, highlighting the value of these therapies for recurrent focal disease.
Glioblastoma multiforme is the most common and aggressive primary malignant brain tumor in adults. Despite recent advances in neuroimaging, surgical techniques, and adjuvant therapies such as chemotherapy and EBRT, GBM has a dismal prognosis, with local recurrence remaining the most common form of relapse in more than 80% of patients. Surgical treatment of a focal recurrence can lead to prolonged growth control, but this procedure is only offered to a small subpopulation. Systemic chemotherapy provides a modest survival advantage, with the median survival ranging from 4 to 7 months in patients with recurrent disease. Stereotactic radiosurgery, fSRT, and brachytherapy are logical adjuncts to current state-of-the-art treatments for recurrent GBM because of their ability to deliver high doses of radiation to a focal target. In comparing these options, radiosurgery appears to be the most convenient, offering a fast, noninvasive treatment that can be completed in one day, is usually well tolerated, and can be repeated.
The main limitation of focal treatments is their inability to address diffuse disease, which in many cases has already developed microscopic lesions far beyond the limits of appreciable radiological boundaries. Nonetheless, developments in medical imaging have enabled the neurosurgeon to accurately visualize functional and biomolecular data from both the normal and diseased brain. New modalities of information may complement simple anatomical representations of the brain to facilitate safer and more efficient therapeutic approaches to brain tumors. In particular, the inclusion of PET and MR spectroscopic, fMR, and diffusion tensor imaging in treatment planning can enhance the coverage of diseased brain areas by showing the diffusion of gliomas along pathways following the subcortical fiber tracts, the presence of distant regions of hypermetabolism, and the involvement of critical areas. This information can help define a planning target volume that is not simply a geometrical expansion of the gross tumor volume.
On these bases, the ability to deliver focal high-dose radiation, ablating a selected volume while preserving normal tissue, has a valuable role in the global treatment of recurrent disease. A number of early retrospective studies on the use of SRS and fSRT for recurrent GBM have shown promise. In this paper, we discuss the role of SRS and fSRT in the multimodal treatment of this disease, with particular emphasis on the treatment of focal relapse.
Abstract and Introduction
Abstract
Glioblastoma multiforme (GBM) is a devastating malignant brain tumor characterized by resistance to available therapeutic approaches and relentless malignant progression that includes widespread intracranial invasion, destruction of normal brain tissue, progressive disability, and death. Stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT) are increasingly used in patients with recurrent GBM to complement traditional treatments such as resection, conventional external beam radiotherapy, and chemotherapy. Both SRS and fSRT are powerful noninvasive therapeutic modalities well suited to treat focal neoplastic lesions through the delivery of precise, highdose radiation. Although no randomized clinical trials have been performed, a variety of retrospective studies have been focused on the use of SRS and fSRT for recurrent GBMs. In addition, state-of-the-art neuroimaging techniques, such as MR spectroscopic imaging, diffusion tensor tractography, and nuclear medicine imaging, have enhanced treatment planning methods leading to potentially improved clinical outcomes. In this paper the authors reviewed the current applications and efficacy of SRS and fSRT in the treatment of GBM, highlighting the value of these therapies for recurrent focal disease.
Introduction
Glioblastoma multiforme is the most common and aggressive primary malignant brain tumor in adults. Despite recent advances in neuroimaging, surgical techniques, and adjuvant therapies such as chemotherapy and EBRT, GBM has a dismal prognosis, with local recurrence remaining the most common form of relapse in more than 80% of patients. Surgical treatment of a focal recurrence can lead to prolonged growth control, but this procedure is only offered to a small subpopulation. Systemic chemotherapy provides a modest survival advantage, with the median survival ranging from 4 to 7 months in patients with recurrent disease. Stereotactic radiosurgery, fSRT, and brachytherapy are logical adjuncts to current state-of-the-art treatments for recurrent GBM because of their ability to deliver high doses of radiation to a focal target. In comparing these options, radiosurgery appears to be the most convenient, offering a fast, noninvasive treatment that can be completed in one day, is usually well tolerated, and can be repeated.
The main limitation of focal treatments is their inability to address diffuse disease, which in many cases has already developed microscopic lesions far beyond the limits of appreciable radiological boundaries. Nonetheless, developments in medical imaging have enabled the neurosurgeon to accurately visualize functional and biomolecular data from both the normal and diseased brain. New modalities of information may complement simple anatomical representations of the brain to facilitate safer and more efficient therapeutic approaches to brain tumors. In particular, the inclusion of PET and MR spectroscopic, fMR, and diffusion tensor imaging in treatment planning can enhance the coverage of diseased brain areas by showing the diffusion of gliomas along pathways following the subcortical fiber tracts, the presence of distant regions of hypermetabolism, and the involvement of critical areas. This information can help define a planning target volume that is not simply a geometrical expansion of the gross tumor volume.
On these bases, the ability to deliver focal high-dose radiation, ablating a selected volume while preserving normal tissue, has a valuable role in the global treatment of recurrent disease. A number of early retrospective studies on the use of SRS and fSRT for recurrent GBM have shown promise. In this paper, we discuss the role of SRS and fSRT in the multimodal treatment of this disease, with particular emphasis on the treatment of focal relapse.
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