Purpose: This study is a retrospective analysis to evaluate the impact of fractionated stereotactic radiotherapy (FSRT) on malignant glioma. Material and Methods: Between June 1996 and May 1998, 37 patients with histology-cally proven WHO grade III or IV glioma (17 Anaplastic astrocytoma, 20 Glioblastoma multiforme) were treated at Taipei Medical University hospital with FSRT. External beam radiotherapy (EBRT) delivered a median dose of 46 Gy which is followed by stereotactic radiotherapy. A frameless fractionated stereotactic radiotherapy was used to boost the tumor bed, using daily fraction of 2.0 -3.0 Gy for 5 to 12 fractions. Non-coplanar arcs (4-8 arcs, median 4 arcs) with 1 to 2 isocenters were mostly used. Survival curves were calculated using the Kaplan-Meier method. Prognostic factors and different treatment variables were tested by univariate and multivariate analysis. Results: Overall median survival was 22 months. One year and 2-year survival rate were 60% and 30% respectively. Follow up imaging study showed tumor reduction greater than 50% in 6 patients (16%), reduction less than 50% or unchanged in 14 patients (38%) and progression in 17 of the 37 patients (46%). On analysis of different prognostic factors, patient's age (＜50 years and≧50 years), extent of surgical resection, and tumor volume (＜20 ml) were correlated with survival in univariate analysis (p＜0.05). Tumor volume and extent of surgical resection remained significant in multivariate analysis. The performance status remained stable for all patients during FSRT and only 5 patients (13%) suffered from treatment related acute toxicity with good medication control. Conclusion: Fractionated stereotactic radiotherapy provides a safe and feasible technique in the primary treatment of malignant gliomas. Although the overall survival and 1 year survival is encouraging, we did not observe a significant dose-effect relationship on overall and progression-free survival. Large series study with long term fallow-up is indicated.
- Stereotactic radiotherapy