SURG-07. CIRCUMFERENTIAL RESECTION OF GLIOBLASTOMA: A NOVEL SURGICAL TECHNIQUE FOR MAXIMISING EXTENT OF RESECTION AND PROLONGING SURVIVAL

Evidence suggests that cytoreduction is associated with improved survival in glioblastoma (GBM) and that maximal, or gross total resection of the tumor offers the best chance for prolonged survival. We developed a novel surgical technique for removal of GBM called Circumferential resection during which we identify the interface between the enhancing rim of GBM and surrounding brain structures enabling more complete resection. We evaluate the impact of this method on extent of resection and survival in glioblastoma. We retrospectively evaluated 127 consecutive patients with newly diagnosed GBM treated at our institution. Forty-seven (37%) had circumferential resection (CR) by the senior author and the other 80(63%) had debulking/piecemeal (“non-circumferential”) resection(NCR). All patients underwent adjuvant chemoradiotherapy as per the Stupp protocol. Tumor volumetric analysis was performed using Osirix software. Overall survival and survival as stratified by treatment and extent of resection (EOR) were evaluated using Kaplan-Meier survival analysis. Clinical characteristics between CR and NCR cohorts were similar. Mean age at diagnosis was 59 years and 81(63.9%) were male. Pre-operative tumor volume was 31.8 cm3 vs. 40.6 cm3 (p=0.05) for CR vs. NCR respectively. Patients who had CR had higher median EOR (100.0 vs. 90.4, p<0.0001). The median OS for the entire cohort was 13.2 months. Median OS for CR and NCR was 17.7 and 11.0 months respectively (p<0.0001). EOR significantly impacted survival. Among the CR cohort, median survival was 22.5 and 11.5 months for >98% and <98% EOR respectively while median survival for the NCR cohort was 14.4 and 9.6 months for >98% and <98% EOR respectively. Post-operative Karnofsky Performance Scale (median, interquartile range) was 80(70-90) and 70(70-90) for CR and NCR patients respectively (p=0.43). Circumferential resection helps maximise the extent of resection in glioblastoma surgery and significantly prolongs survival without compromise to functional status.