RT-14 * TIME TO RADIATION THERAPY IN GLIOBLASTOMA MULTIFORME: IS SOONER BETTER?

INTRODUCTION: Optimal post-surgical treatment of glioblastoma multiforme (GBM) includes concurrent radiation therapy and temozolomide. However, there is conflicting data regarding the ideal timing of radiation. Proponents of early therapy cite the rapid proliferation rate of WHO grade IV tumors and advocate treatment with minimal delays. Others believe extra time allows the surgical cavity to collapse and tempers the risk of infection, minimizing complications from radiation. METHODS: We retrospectively reviewed records of 97 patients with a pathologic diagnosis of GBM at our institution who underwent postoperative treatment with at least 6 weeks of radiation according to Radiation Therapy Oncology Group guidelines and concurrent temozolomide therapy. Demographic, clinical, radiographic and operative data were reviewed. Analysis of variance(ANOVA) was used to identify differences between surgical and demographic subgroups. Kaplan-Meier survival analysis was used to estimate overall(OS) and progression free survival(PFS). Cox regression analyses were performed to determine the effect of radiation timing on survival. RESULTS: 49 male and 47 female patients had a median age at surgery of 57 years (range 18-77). Sixteen patients underwent biopsy, 64 had a subtotal resection(STR) and 16 had a gross total resection(GTR). One year OS and PFS were 70% and 16%, respectively. The median time to radiation(TTR) was 26 days (range 9-51 days). TTR was significantly longer in patients with resection compared to biopsy (p < 0.001). TTR did not significantly affect OS (p = 0.732) or PFS (p = 0.699) of the entire cohort or the subgroup treated with resection (OS, p = 0.809; PFS, p = 0.812). CONCLUSIONS: The precise timing of radiation initiation does not appear to affect survival of patients with GBM who are optimally treated with radiation and temozolomide. Therefore practitioners may allow extra time within the recommended 6 week window for optimal medical stabilization and wound healing without fear that this may adversely affect patient outcomes.