The Survival Advantage of Supratotal Resection of Glioblastoma Using Selective Cortical Mapping and the Subpial Technique

BACKGROUND: A substantial body of evidence suggests that cytoreductive surgery is a prerequisite to prolonging survival in patients with glioblastoma (GBM). OBJECTIVE: To evaluate the safety and impact of supratotal resections beyond the zone of enhancement seen on magnetic resonance imaging scans, using a subpial technique. METHODS: We retrospectively evaluated 86 consecutive patients with primary GBM, managed by the senior author, using a subpial resection technique with or without carmustine (BCNU) wafer implantation. Multivariate Cox proportional hazards regression was used to analyze clinical, radiological, and outcome variables. Overall impacts of extent of resection (EOR) and BCNU wafer placement were compared using Kaplan-Meier survival analysis. RESULTS: Mean patient age was 56 years. The median OS for the group was 18.1 months. Median OS for patients undergoing gross total, near-total, and subtotal resection were 54, 16.5, and 13.2 months, respectively. Patients undergoing near-total resection (P = .05) or gross total resection (P <. 01) experienced statistically significant longer survival time than patients undergoing subtotal resection as well as patients undergoing >= 95% EOR (P < .01) when compared to <95% EOR. The addition of BCNU wafers had no survival advantage. CONCLUSIONS: The subpial technique extends the resection beyond the contrast enhancement and is associated with an overall survival beyond that seen in similar series where resection of the enhancement portion is performed. The effect of supratotal resection on survival exceeded the effects of age, Karnofsky performance score, and tumor volume. A prospective study would help to quantify the impact of the subpial technique on quality of life and survival as compared to a traditional resection limited to the enhancing tumor.