P13.06 * IS SAFE TO COMBINE HYPOFRACTIONATION AND LOW DOSE FRACTIONATED RADIATION THERAPY WITH TEMOZOLOMIDE IN NAIVE UNRESECTABLE GLIOBLASTOMA? - RESULTS OF A PILOT STUDY

Abstract

OBJECTIVE: To explore safety and efficacy of hypofractionated radiotherapy (HyRT) followed by low dose radiation therapy (LDRT) in combination with Temozolomide (TMZ) in adults with newly diagnosed Glioblastoma Multiforme. MATERIAL AND METHODS: Patients (ECOG ≤2, age ≥18 years) with a previous biopsy or a gross residual tumor after surgery were enrolled in this study. Treatment started with HyRT (30 Gy in ten fraction) combined with TMZ (75 mg/m2 for all time of RT) followed by adjuvant TMZ. From the second to third cycle of adjuvant TMZ, LDRT (0.40 Gy twice daily, at least 4 hours apart over 5 consecutive days, every 28 days) was planned. Another 2 cycles were scheduled if neither progression disease nor clinical decrease was observed. Conformal irradiation included the tumor with surgical cavity, plus a 30-mm margin. The primary endpoints were safety, tolerability and toxicity according to Common Terminology Criteria for Adverse Events version 4.0. Response according to RANO Guidelines, Overall Survival, Progression-free survival (PFS) were the secondary endpoints. RESULTS: From June 2008 to January 2012, 20 patients with a median age of 64.5 years were enrolled. All patients received the prescribed dose of 30 Gy. 17 out of twenty received 2 cycles of LDRT and the median total dose was 12 Gy. All toxicities were reversible and only 5 patients presented hematologic G1-2 toxicity. At the end of the fourth cycle, 4 out of 20 patients had partial response, 6 experienced stable disease and 10 patients had progressive disease Median OS and PFS from diagnosis were 14 and 11 months, respectively. Patients who received ≤2 cycles presented a median OS and PFS of 5 and 4 months respectively; when four cycles were administered the median OS was 26 months and PFS was 14 months. CONCLUSIONS: Hypofractionated regimen followed by LD-FRT combined with TMZ is safe and tolerated well. The number of LDFRT's cycles seems to increase the survival in this setting of patients. A new study is ongoing.