P07.11.A Impact of awake craniotomy on extent-of-resection and performance in glioma: a retrospective, propensity-score matched cohort study

Abstract

Abstract Background The goal of awake craniotomy is to safely optimize the extent-of-resection in patients with glioma. Lower postoperative tumor volume is associated with better overall survival, emphasizing the importance of optimal surgical resection. Awake craniotomy causes less postoperative neurological deficits than surgery under general anesthesia, however, it is unclear whether awake craniotomy leads to lower postoperative tumor volume compared with general anesthesia in presumed lower grade glioma. Methods Retrospective, matched cohort study in patients with astrocytoma, IDH-mutant grade 2 and 3, oligodendroglioma, IDH-mutant, and 1p/19q-codeleted grade 2 and 3, and low-grade glioma, IDH-wildtype (now designated glioblastoma, IDH-wildtype), who underwent resection with awake craniotomy or under general anesthesia between 2003 and 2021 at Erasmus MC Brain Tumor Center. Pre- and postoperative tumor volumes were measured by semi-automatic 3D MRI-segmentation. First, we performed a multivariate logistic regression to assess which factors predicted selection for awake craniotomy. Thereafter, matching based on propensity score was attempted. Outcome variables were postoperative tumor volume, resection percentage and Karnofsky Performance Status (KPS) 3 months after surgery. Results We identified 181 awake craniotomy-patients and 135 general anesthesia-patients. Awake craniotomy-patients were younger, in better condition, more often male, with tumors more often in eloquent areas, in the left side of the brain and non-contrast enhancing. When performing matching without replacement, only 68 awake craniotomy-patients could be matched with 68 general anesthesia-patients, underscoring the imbalance in the dataset. Matching with replacement yielded a matched dataset of 181 awake craniotomy-patients with 60 general anesthesia-patients with adequate matching on most baseline variables, except for eloquent area (47% for awake craniotomy and 21.7% for general anesthesia, p < 0.001). In this matched dataset, median postoperative volume in awake craniotomy was 5.8 mL (IQR 0 - 92.8) vs 12.2 mL (IQR 0 - 90.1) in general anesthesia (p-value = 0.114). Resection percentages did not differ between the awake craniotomy- and general anesthesia-groups. KPS scores at 3 months after surgery did not differ between awake craniotomy and general anesthesia (p = 0.15). Conclusion Postoperative tumor volume was not lower in awake craniotomy-patients than in general anesthesia-patients. Neither were resection percentage and KPS scores at 3 months after surgery significantly different between the groups. Adequate matching was only obtainable using replacement, underscoring the risk of bias in unmatched datasets. These data should be interpreted with care, given the retrospective nature, potential residual confounding and potential lack of generalizability due to unmatched normal resection patients.