RADT-23. IMPACT OF REIRRADIATION UTILIZING STEREOTACTIC RADIOSURGERY ON RECURRENT GLIOBLASTOMA

Abstract

Abstract BACKGROUND Patients who have recurrent glioblastoma have limited treatment options. We conducted a retrospective review of patients with recurrent glioblastoma treated with standard initial radiation and temozolomide with tumor treating fields to investigate whether reirradiation using radiosurgery would be associated with improved outcomes. METHODS We reviewed the records of 54 consecutively treated patients with recurrent glioblastoma with ECOG 0 or 1 at recurrence and conducted Kaplan-Meier analysis with Log-rank testing to determine significance between groups. RESULTS We identified 24 patients who were treated without radiation therapy (control) while 30 patients underwent re-irradiation using radiosurgery (ReSRS) with a median total dose of 25Gy in five fractions. All patients had completed standard initial therapy, and there was no difference in the time to recurrence between the two groups (10 months for control, 15 months for ReSRS, [P = 0.17, HR for progression 0.65 (95% CI 0.38-1.13)]. A larger proportion of patients in the control arm (54%) had subtotal or gross total resection of the recurrence compared with the ReSRS group (44%, P < 0.05). The majority of patients had recurrence confirmed with biopsy (18/22 in control group, 25/31 in the ReSRS group). MGMT methylation status did not differ between control vs ReSRS (29% vs. 27%). ReSRS was associated with improved median survival from the time of first recurrence of 11.6 months versus 3.8 months in the control arm [P< 0.0001, HR for death 0.33 (95% CI 0.18-0.6)]. CONCLUSIONS In a group of patients with high performance status diagnosed with recurrent glioblastoma, reirradiation with stereotactic radiosurgery was associated with nearly one year median survival after recurrence. Additional analyses are warranted to determine the impact of concurrent systemic therapies with irradiation and underlying tumor or patient factors to predict outcomes.