RT-05 THE RESULTS OF GAMMA KNIFE RADIOSURGERY WITH BEVACIZUMAB (AVAGAMMA THERAPY) FOR RECURRENT GRADE II/III GLIOMAS

BACKGROUND: For primary grade II/III glioma, we usually combine radiation therapy and chemotherapy after surgical resection. However, the treatment of recurrent grade II/III glioma is controversial. For lesions that can be safely resected, the second surgery may be optimal, but grade II/III glioma often occurs in or near the eloquent areas, so partial resection is often performed. In such cases, if a second surgery for the recurrent tumor is performed, total resection is often difficult. We have performed gamma knife radiosurgery with concurrent bevacizumab (GKRS with Bev) as salvage therapy for recurrent grade II/III gliomas, which were considered difficult to resect. OBJECTIVE: To investigate the outcome of GKRS with Bev for recurrent grade II/III gliomas. <Methods> We retrospectively reviewed initial pathological findings, PFS/OS from GKRS with Bev, and OS from initial treatment for 23 cases receiving GKRS with Bev for recurrent grade II/III gliomas at our institution between August 2013 and March 2019. RESULTS: In the initial pathological findings, grade II were 8 cases (DA: 7, OD: 1), and grade III were 15 cases (AA: 14, AOA: 1). Regarding IDH mutations, in grade II, 3 cases were mutant type, 2 cases were wild type, and 3 cases were unknown. Similarly, in grade III, 5, 6, and 4 cases, respectively. From salvage therapy, PFS was median 6 months in grade II and 8 months in grade III, and OS was median 11 months in grade II and 16 months in grade III. From the initial treatment, OS was median 95 months in grade II, and 38 months in grade III. CONCLUSION: Because most of our cases were astrocytic tumors, when they relapsed, it seemed that some of them progressed to glioblastoma. Even in these severe cases, GKRS with Bev can play an important role as salvage therapy.