OS02.7.A The role of epilepsy in elderly patients with Glioblastoma: An Austrian multicenter analysis

Abstract Background Higher age is a significant predictor of poor outcome in glioblastoma multiforme (GBM) patients. Thus, acquisition of a better understanding of additional prognostic factors in these often-frail patients is of utmost importance. Epileptic seizures correlate with improved overall survival (OS) in low-grade gliomas; however, the impact of epilepsy in GBM patients on outcome parameters is poorly defined. Furthermore, persisting epilepsy significantly influences the patients’ quality of life (QoL). This study aims at specifically evaluating the impact of epilepsy in elderly GBM patients. Material and Methods Two Austrian academic neurosurgical centers retrospectively analyzed all elderly (≥65 years) GBM patients with de-novo tumors, who underwent tumor resections between 09/2006 and 07/2021. Epidemiological, histopathological and survival data were gained from patients’ electronic charts and screened for presence of epilepsy preoperatively or during follow-up. Results 391 patients (55% males, 45% females) with a median age at surgery of 73 years (Interquartile Range (IqR) 68.5-77.5) were analyzed. The mean predicted OS was recorded to be 12.4 months (CI95% 10.9-14.0). Median preoperative Modified Rankin Scale (mRS) was 2 (IqR 1-3), and median preoperative Karnofsky performance score was 80 (IqR 60-90). Mean follow-up was 10.4 months (CI95% 9.1-11.6) in our cohort. 95/391 patients (24%) suffered from preoperative epilepsy. 17 (18%) patients still suffered from epilepsy after tumor resection with eight patients who developed new postoperative seizures, and four patients (1.0%) showed a worsening of already preoperatively diagnosed seizures. Major surgery-associated neurological complications included new motor deficits in 29 (7%) and new aphasia in 16 (4%) patients. Logistic regression showed, patients with seizures had significantly lower mRS (OR=0.735 [CI95% 0.563 0.961], p=0.032) and less frequently occipital tumor location (OR=0.347 [CI95% 0.152-0.791], p=0.018). Postoperative epilepsy resulted in significantly prolonged hospitalization after the surgery (OR=2.622[CI95% 1.496-3.979], p=0.009). Survival did not correlate with preoperative epilepsy (p>0.05). However, Cox regression revealed that multifocal tumor location (HR=1.777 [CI95% 1.197-2.639], p=0.025) as well as thalamic involvement (HR=11.121 [CI95% 3.431-36,046], p=0.030) negatively influenced OS. Furthermore, surgery-associated complications shortened OS significantly (HR=1.945