10039- RT-1 TREATMENT RESULTS OF AVAGAMMA THERAPY FOR RECURRENT GLIOBLASTOMA COMBINED WITH GAMMA KNIFE AND BEVACIZUMAB

Abstract PURPOSE We report the treatment results of AVAgamma therapy combining gamma knife (GK) and bevacizumab (Bev) for recurrent glioblastoma. SUBJECTS From August 2013 to July 2024, 68 patients with recurrent glioblastoma treated with AVAgamma therapy as salvage therapy at the time of relapse after initial treatment. When the GK irradiated volume was 15 ml or less, a borderline dose of 20-26 Gy was administered in a single fraction, and when it was greater than that, a borderline dose of 24-30 Gy was administered in 2-5 fractions. The mean therapeutic marginal dose was 24 Gy. Bev was administered 10 mg/kg or 15 mg/kg 1 to 10 times after GK. METHODS Median progression-free survival (mPFS) and median survival (mOS) from AVAgamma treatment, and mOS and 5-year survival rate from initial treatment were compared with historical controls (GK group: 30 patients) who received only GK at the time of recurrence. RESULTS The mPFS from AVAgamma therapy was 6 months, PFS-6month was 40%, OS-6month was 77%, and mOS was 11 months. The mOS from initial treatment was 25 months, which was prolonged compared to 21 months in the GK group (p=0.05). The 5-year survival rate for recurrent glioblastoma was 5% in the GK group and 22% in the AVAgamma group (p=0.05). The 5-year survival rate for glioblastoma with KPS>70% at recurrence was 0% in the GK group and 27% in the AVAgamma group (p=0.14). DISCUSSION Combined use of Bev with GK was considered to provide local control of recurrent lesions and prolong life prognosis in patients with good KPS at the time of recurrence. CONCLUSION AVAgamma therapy is thought to prolong the survival of recurrent glioblastoma and play an important role as salvage treatment.