The efficacy of radiation therapy in the management of grade I astrocytomas

Introduction: The purpose of this study was to analyze the outcome of patients with grade I astrocytomas treated with radiation therapy, specifically looking at the prognostic significance of age, timing of radiation therapy (immediately after surgery or delayed until progression) and tumor location. Materials and methods: The records of patients with grade I astrocytomas treated at Washington University Medical Center between 1982 and 2002 were reviewed. Twenty patients with grade I pilocytic astrocytoma (n=19) or subependymal giant cell astrocytoma (n=1) were treated with radiation therapy with curative intent. Results: The median follow-up was 6.4 years. The 5-year overall survival for all patients was 100%. The 5-year progression-free survival (PFS) following radiation therapy for all patients was 68%. Patients who received radiation therapy immediately after biopsy or surgery had a 5-year PFS of 77% versus 50% for patients who received radiation therapy after initial disease progression (P=0.013). Patients with infratentorial tumors had an improved outcome with a 5-year PFS of 80% versus 59% for those with supratentorial tumors (P=0.0076). Patient age did not significantly influence outcome. All tumor recurrences were local. Conclusions: While this study reports an excellent overall survival, approximately one third of patients with grade I astrocytomas had progressive disease following radiation therapy. In particular, patients with supratentorial tumors and delayed radiation therapy had a worse PFS. Additional investigation is needed to improve the outcome in these patients.