Stereotactic Radiosurgery in the Management of Intracranial Gliomas

Abstract

Glial neoplasms are the most common primary intracranial malignancies. Treatment of high-grade gliomas has been frustrating, with less than 5% of patients surviving 5 years after a diagnosis of glioblastoma multiforme (GBM). Stereotactic radiosurgery (SRS) and fractionated strereotactic radiotherapy (F-SRT) provide means to either escalate the dose in primary treatment or to palliate recurrences. Because of their lower alpha/beta ratios and more focal nature, low-grade gliomas (LGG) are more attractive targets for stereotactically focused radiation. Results of available phase I-II data are reviewed for both low and high-grade gliomas. In the case of high-grade gliomas disappointing preliminary phase III data from RTOG 93-05 are discussed. Toxicity of SRS is discussed. Acute treatment toxicity of significance is unusual and generally self-limited. Occasionally an exacerbation of existing symptoms occurs. Late complications attributable to SRS are usually defined as necrosis within the treatment volume. The rate of necrosis can be hard to define in high-grade gliomas as tumor cells are often present in surgical specimens. New strategies in the application of stereotactic radiation are touched upon, these include: changes in planning and fractionation, concurrent use of chemotherapy, use of radiation modifiers and biologic agents. After reviewing the current data for high-grade gliomas, it appears that any apparent improvement in outcome seen in phase I-II trials is attributable to patient selection. The best evidence available does not support the use of SRS for primary high-grade gliomas. The somewhat limited experience in LGG also indicates a lack of benefit for patients treated with stereotactic radiosurgery or F-SRT. For a very select group of patients with small recurrent lesions, F-SRT may represent a safe, reasonable treatment.

Indications and Efficacy of Gamma Knife Stereotactic Radiosurgery for Recurrent Glioblastoma: 2 Decades of Institutional Experience

“…These data are consistent with outcomes from growing literature (Table 7) that tends to conclude that GK is safe and modestly effective for recurrent disease. 50,51 Across these series, median post-GK OS ranges from 3.9–30 months; 52,53 however, most report 9–13 months.…”

Convection-enhanced delivery of nanocarriers for the treatment of brain tumors

“…A stereotactic head frame is based on a 3D coordinate system consisting of three orthogonal planes, which are related to external skull points. Stereotaxy can be used to approach deep-seated brain lesions with a probe, a cannula or a high energy ionizing radiation beam [35].…”

Effect of Carbogen Breathing on the Radiation Response of a Human Glioblastoma Xenograft

“…The three resistance mechanisms that are most important for radiation treatment failure are intrinsic radiation resistance, tumor cell repopulation during treatment, and tumor hypoxia. Intrinsic radioresistance can be counteracted by increasing the total tumor dose, by using for instance, radiosurgery or stereotactic radiotherapy which is, however, limited to smaller tumors [34] or by combining radiotherapy with 2-deoxy-d-glucose [42]. Intraoperative radiotherapy also resulted in a slightly improved survival in GBM [39].…”