P13.03 * HYPOFRACTIONATED STEREOTACTIC RADIOTHERAPY (HSR) IN RECURRENT HIGH GRADE GLIOMA: A SAFE AND EFFECTIVE APPROACH

Abstract

PURPOSE: Tumor control and survival in patients with high grade glioma (HGG) are limited. Local recurrence occurs usually in primary site within 1-3 years from initial treatment. Treatment at recurrence are not standardized and various therapeutic approach can be used. Hypofractionated Stereotactic Radiotherapy (HSR) has been shown as a feasible and effective treatment for recurrent high grade glioma previously treated with conventional radiotherapy. HSRSallows a precise delivery of radiation with optimal sparing of normal and functional brain in eloquent areas. In addition, hypofractionation of delivery dose could get a potential radiobiological advantage on tumor cells. The aim of this study is to evaluate safety and efficacy of salvage HSRS in recurrent high grade glioma patients. End points of the analyses are toxicity, rate of local control and patient's survival. MATERIALS AND METHODS: Adult patients with Karnosky Performance Status (KPS) ≥70 and a disease free interval higher than 1 year were included. Gadolinium- MRI and C11METPET were performed before and every 3 months thereafter. The Median dose delivered on the PTV was 25 Gy (range 25-50 Gy) in 5 fractions (range 5-10). Volumetric Modulated Arc therapy (VMAT) by Rapid Arc (RA) technique was used. Response and toxicity were evaluated using RANO criteria and CTCAE 3.0 respectively. RESULTS: Between January 2006 and December 2013, 25 patients (15 males and 10 females) were treated; the median age was 41 years (range 26-75 years). Sixteen of them had Glioblastoma, 5 Anaplastic Oligoastrocytoma and 4 Anaplastic Astrocytoma. At recurrence, before HSR 9 patients underwent partial surgical resection and 5 received a second line chemotherapy > Median time between the first RT treatment and HSRS re- irradiation was 18 months (range 12-77 months). The Median follow up was 11.1 months (1.3-19.2 months). No G3-G4 toxicity was observed. Response in according to RANO criteria was recorded in 14 patients (56%). Median survival was 11.5 months (range 1.3-19.2 months). PFS at 1 year was 30% and OS at 1 and 2 years were 40% and 20%. At the last follow up 12 patients were alive and 13 died. CONCLUSION: HSR re-irradiation is a feasible, safe and effective therapeutic option for patients with recurrent HGG. VMAT RA technique improves target coverage while minimizing higher dose to normal tissue with remarkable radiological and clinical response and negligible toxicity.