Single-Fraction Radiosurgery for Primary and Recurrent Malignant Gliomas

Abstract

From November 1990 to May 1993, 37 patients with malignant gliomas were treated with single-fraction radiosurgery. Nineteen patients had newly diagnosed tumors. Twelve of these were gliob-lastoma multiforme (GBM) and 7 were anaplastic astrocytoma (AA). Tumors were recurrent after standard radiotherapy in 18 patients. Twelve were GBM and 6 were AA. Median ages were 56 years for those with primary tumors and 52 years for those with recurrent tumors. Strict neuroimaging criteria were not used to select patients for radiosurgery. Median tumor volumes for primary GBM and AA were 15 cc and 9.4 cc, respectively. Median volumes for recurrent GBM and AA were 22.6 cc and 19.6 cc, respectively. Karnofsky Performance Status was above 60% in all patients. Median tumor minimum doses were 30 Gy for primary tumors and 27 Gy for recurrent tumors. Median tumor maximum doses were 50 Gy and 55 Gy, respectively. Median follow-up was 14 months for primary glioma patients and 7.5 months for those with recurrent tumors. Survival analysis was performed using the Kaplan–Meier method. Comparison of prognostic factors was performed using the log-rank and Wilcoxon tests No patient in this series remains alive. Median survivals of those with primary GBM and AA were 13 and 12 months, respectively, from diagnosis. Median survivals of those with recurrent GBM and AA were 7 and 8 months, respectively, from the date of radio-surgery. Thirty-three of 37 patient deaths were due to tumor progression within the radiosurgery treatment volume. Tumor recurred outside the high-dose volume of radiosurgery in 3 patients. Acute complications necessitating hospitalization occurred in 3 patients. Fourteen patients (38%) became dependent on corticosteroids after radiosurgery. Six patients (16%) were resected after radiosurgery. Coagulative necrosis and morphologically intact tumor cells were identified in all resected patients. There was no significant influence of the following factors on actuarial survival of primary or recurrent tumors: age, gender, tumor volume, tumor location, duration from conventional radiotherapy, or radiosurgery dose. Tumor volume was a predictor of reoperation for AA. Indiscriminate application of radiosurgery in this series did not increase the survival of patients with primary or recurrent GBM. Central recurrence represents the predominant form of relapse when patients with malignant gliomas receive radiosurgery in the absence of imaging selection criteria. These criteria include tumor volume and evidence for a discreet lesion. Radiosurgery planning should provide a margin of normal brain parenchyma. Advances in tumor imaging and radiosurgery techniques may improve results of this unique modality for patients with malignant gliomas.