2646 - The Use of Tumor Treating Fields Therapy for Newly Diagnosed Glioblastoma in Elderly Populations: A Single-Institution Study
Presenter(s)
C. A. Owens1, J. Pan1, E. Lesha2, D. C. Portnoy3, J. Sorenson2,4, L. M. Michael2,4, and M. T. Ballo3,5; 1University of Tennessee Health Science Center College of Medicine, Memphis, TN, 2Department of Neurosurgery, University of Tennessee Health Science Center, Memphis, TN, 3West Cancer Center and Research Institute, Germantown, TN, 4Semmes-Murphey Neurosurgery Clinic, Memphis, TN, 5Cleveland Clinic Foundation, Cleveland, OH
Purpose/Objective(s): Glioblastoma (GBM) is a highly aggressive brain tumor with poor prognosis, particularly in elderly patients. Tumor Treating Fields (TTFields) therapy has shown survival improvement when combined with standard treatment, but data on its utilization and efficacy in older patients are limited. This study evaluates the impact of TTFields on overall survival (OS) in elderly patients, by assessing TTFields compliance and its association with clinical outcomes. We hypothesize that higher compliance with TTFields therapy is associated with improved OS in patients aged =65 years with newly diagnosed GBM.
Materials/Methods: Patients were retrospectively identified from a single-institution database. Inclusion criteria included IDH wild-type supratentorial GBM, maximal surgical resection or biopsy, completion of external beam radiotherapy with concurrent temozolomide (TMZ), and initiation of adjuvant therapy, which yielded 126 patients. Focusing on patients 65 years or older resulted in a study group of 41. TTFields compliance data were collected monthly, and patients were categorized into three groups: no use, low use (compliance <75% or use <2 months), and high use (compliance =75% for =2 months). Patients were also grouped into a 50% compliance threshold. Chi-squared and Fisher’s exact tests were used to compare categorical variables. OS was analyzed using Kaplan–Meier survival curves, with multivariate analysis to account for confounding factors.
Results: Among 41 elderly patients, the 1-, 2-, and 3-year OS rates were 62%, 25%, and 17%, respectively. Only 46% (18/41) of these patients initiated TTFields therapy, a significantly lower rate compared to 66% (56/85) in patients under 65 (p = 0.036). TTFields adherence did not significantly differ by sex, MGMT methylation status, ECOG performance, radiation dose, or extent of surgical resection. Though not statistically significant, 2-year actuarial OS showed an upward trend with increased TTFields use (Use | %OS): No use | 17%, Low use (<75%) | 34%, High use (=75%) | 37%. When categorized differently, OS rates at 2 years were: No use | 17%, <50% use | 24%, =50% use | 37%.
Conclusion: This study suggests TTFields therapy can be effectively integrated into the standard treatment regimen for elderly patients with newly diagnosed GBM, with improved survival correlating with higher compliance. However, TTFields initiation rates were significantly lower in elderly patients compared to younger patients, highlighting a potential gap in care. While the observed trends in overall survival support the benefits of TTFields, statistical significance was not reached, emphasizing the need for larger, prospective studies. Future research should focus on identifying and addressing barriers to TTFields adoption in elderly patients to optimize its utilization and improve clinical outcomes in this high-risk population.