The role of stereotactic radiosurgery for low-grade astrocytomas.

Hadjipanayis CG, Neurosurg Focus. 2003 May 15;14(5):e15.

Department of Neurological Surgery, Center for Image-Guided Neurosurgery, University of Pittsburgh Medical Center,

OBJECT: This study was conducted to examine the role of radiosurgery in the management of patients with recurrent or unresectable low-grade astrocytomas. METHODS: During a 13-year interval, 49 patients underwent stereotactic radiosurgery as part of multimodal treatment of their recurrent or unresectable low-grade astrocytomas. Thirty-seven of these patients (median age 14 years) harbored pilocytic astrocytomas and 12 patients harbored World Health Organization (WHO) Grade II fibrillary astrocytomas (median age 25 years). Tumors involved the brainstem in 22 cases, cerebellum in four, thalamus in six, temporal lobe in five, frontal lobe in four, and parietal lobe in three, as well as the hypothalamus, corpus callosum, insular cortex, optic tract, and third ventricle in one patient each. Each diagnosis was confirmed with the aid of stereotactic biopsy sampling in 17 patients, open biopsy sampling in five, partial resection in 13, and near-total resection in 14. Multimodal treatment included fractionated radiotherapy in 14 patients, stereotactic intracavitary irradiation in five, chemotherapy in two, cyst drainage in eight, ventriculoperitoneal shunt placement in five, and additional cytoreductive surgery in five.

Tumor volumes ranged from 0.42 to 45.1 cm3. The median radiosurgical dose to the tumor margin was 15 Gy (range 9.6-22.5 Gy). After radiosurgery, serial neuroimaging demonstrated complete tumor resolution in 11 patients, reduced tumor volume in 12, stable tumor volume in 10, and delayed tumor progression in 16. No procedure-related death was encountered. Forty-five of 49 patients are alive at a median follow-up period of 32 months after radiosurgery and 63 months after diagnosis. Sixteen patients participated in follow-up review for more than 60 months. Three patients died of local tumor progression. CONCLUSIONS: Stereotactic radiosurgery is a potential alternative or adjunctive intervention in the management of selected patients with pilocytic or WHO Grade II fibrillary astrocytomas, usually performed for small-volume tumors in an attempt to avoid larger-field fractionated radiotherapy.

Gamma knife radiosurgery for low-grade astrocytomas: results of long-term follow up.

Kida Y, Kobayashi T, Mori Y J Neurosurg. 2000 Dec;93 Suppl 3:42-6.

Department of Neurosurgery, Komaki City Hospital, Japan.

Fifty-one patients with low-grade astrocytomas treated with GKS and followed for more than 24 months are reported. Of the 51 patients, 12 harbored Grade I astrocytomas in and around the visual pathways and hypothalamus. The remaining 39 harbored Grade II astrocytomas. The mean patient age at time of GKS was 9.8 years for patient with Grade I and 30.9 years for those with Grade II astrocytomas. The mean tumor diameter was 25.4 mm for Grade I and 23.7 mm for Grade II tumors. The mean margin dose was 12.5 Gy for Grade I and 15.7 Gy for Grade II tumors. In the mean follow-up period of 27.6 months, both Grade I and Grade II astrocytomas responded well to GKS. Grade I astrocytomas had a response rate of 50% and a control rate of 91.7%. Grade II astrocytomas had a 46.2% response rate and an 87.2% control rate. Statistical analyses concerning the efficacy and related factors showed a significantly better response for patients 10 years of age or older with Grade I and those with a follow-up period of more than 24 months. Complications included radiation-induced edema in 18 (35.3%) of 51 cases, cyst formation or enlargement in five (9.8%), and transient tumor enlargement in three (5.9%). CONCLUSIONS: Radiosurgery can play an important role in the treatment of low-grade astrocytomas, and complete cure of these tumors is expected in at least some of the cases.

The role of the Gamma Knife in the management of cerebral astrocytomas.

Szeifert GT, Prog Neurol Surg. 2007;20:150-63.

National Institute of Neurosurgery and Department of Neurological Surgery, Semmelweis University, Budapest, Hungary.

The aim of this study was to assess the role of Gamma Knife radiosurgery in the complex management of cerebral astrocytomas. Out of a series with more than 1,000 brain tumor cases treated at the Lars Leksell Center for Gamma Knife Surgery, UVA, 74 astrocytomas were selected for the present review. The tumor either disappeared or decreased in 60% of grade 1 astrocytomas (n = 15), and 71% tumor control was achieved in grade 2 astrocytomas (n = 17) following radiosurgery. In the high-grade glioma group (grades 3 and 4; n = 42) median survival time was 14 (range 2-58) months, and 25% of the patients were alive at 5 years after the treatment. The best results were presented by the subgroup wherein previous craniotomy and debulking of the tumor were followed by radiosurgery (n = 7) with a median survival period of 24 (range 2-53) months. Results of the present analysis suggest that stereotactic radiosurgery represents an alternative or supplementary treatment modality to conventional surgery in small-volume low-grade astrocytomas especially in deep-seated critical locations. There is also evidence for the beneficial effect of radiosurgery on the survival of patients with high-grade gliomas; however, the limitations of a focused irradiation technique on a malignant infiltrative process are obvious.