P17.57 * COMBINED CHEMORADIATION IN ELDERLY PATIENTS WITH GLIOBLASTOMA: COMPARISON OF TWO RADIATION SCHEDULES

Abstract

BACKGROUND: Current treatment of glioblastoma (GBM) in the elderly population includes surgery, radiotherapy (RT) and chemotherapy, however the optimal management of disease remains a matter of debate. Both standard and hypofractionated RT in combination with temozolomide (TMZ) have been employed with reported survival benefit; however, aggressive treatments in this population may be associated with high risks of neurological toxicity. We have compared the efficacy of concomitant and adjuvant TMZ in combination with standard RT (60 Gy in 30 fractions) or short-term RT (40 Gy in 15 fractions) in patients aged 70 years and older with a newly diagnosed GBM. PATIENTS AND METHODS: Ninety-five consecutive patients ≥ 70 years old with a newly diagnosed GBM were treated with standard RT plus TMZ at the dose of 75 mg/m2 per day followed by adjuvant TMZ (150-200 mg/m2 for 5 days during each 28-day cycle) up to 12 cycles. Overall survival (OS), progression-free survival (PFS) and toxicity were evaluated and compared with the results observed in a prospective trial of elderly patients with GBM treated with an abbreviated course of RT. RESULTS: Median OS was 12 months in patients treated with standard chemoradiation and 12.4 months in those treated with short-term RT plus TMZ (p= 0.2), and respective 1-year survival rates were 50% and 58%. The median and 1-year PFS rates were 6 months and 23% in standard RT plus TMZ group and 6 months and 20% in short-term RT plus TMZ group, respectively. Grade 3 or 4 hemathological toxicity was similar in both groups. Neurological grade 2/3 toxicity occurred in 35% of patients treated with standard RT/TMZ and 10% of those treated with short-term RT/TMZ. MGMT promoter methylation was associated with longer survival in both groups. CONCLUSIONS: A combination of an abbreviated course of RT plus concomitant and adjuvant TMZ is associated with similar survival benefit as for standard chemoradiation, although with potential lower risks of neurological deterioration. Future randomized studies need to evaluate the efficacy and safety of different schedules of RT in association with chemotherapy.