Tumor treating fields utilization and efficacy for glioblastoma at a large multicenter academic practice

Despite Tumor Treating Fields (TTF) being included in NCCN guidelines as standard treatment for GBM after improving overall survival in a prospective randomized trial, adoption has been limited. We sought to describe utilization, validate the efficacy, and compare patterns of failure after TTF for GBM patients in a real-world dataset.

We identified patients with newly diagnosed GBM between 2014-2023 who received standard fractionation external beam radiotherapy (EBRT). Data collected included extent of resection, radiotherapy dose fractionation and modality, utilization of tumor treating fields, and presence and location of progression based on radiographic findings. Kaplan-Meier (KM) curves were generated for progression-free and overall survival. Patient/disease characteristics in relation to TTF utilization were evaluated between the two groups.

Three-hundred and ninety-three (393) patients were included in this study. 74 patients were treated with TTF (18.8 %). The adoption of TTF utilization increased in 2019 by 10 %. The rate of TTF utilization was approximately 20 % from 2019 to 2023. 2-year OS was improved with the addition of TTF after EBRT (58 % versus 41 %, p < 0.006). On multivariable adjustment, TTF use remained associated with improved OS (p = 0.038). There was a trend towards increased marginal failures and decreased in-field failures with the addition of TTF (p = 0.099).

Widespread adoption of TTF in the treatment of GBM has been generally met with hesitation with less than one-fourth of modern patients receiving TTF. TTF was associated with improved OS, consistent with previously published prospective clinical trial results. Our results also suggest there may be an interplay between TTF and EBRT, affecting pattern of failure, with decreased rates of in-field failure among the TTF group.