Current usage of tumor treating fields for glioblastoma.

Background: Tumor Treating Fields (TTF) have entered clinical practice for newly diagnosed and recurrent glioblastoma (GGM). However, controversies remain unresolved with regard to appropriate usage. We sought to determine TTF usage in major academic neuro-oncology programs in New York City, USA and Heidelberg, Germany and understand current attitudes toward TTF usage among providers.

Methods: We retrospectively determined TTF usage among patients with GGM, before and since the publication of key clinical trial results and regulatory approvals. We also surveyed attendees of an educational session related to TTF during the 2019 American Society of Clinical Oncology annual meeting.

Results: TTF usage remains infrequent (3-12% of patients with newly diagnosed GBM, and 0-16% of patients with recurrent disease) in our practices, although it has increased over time. Among 30 survey respondents (77% of whom self-identified as neuro- or medical oncologists), 60% were convinced that TTF prolongs survival for newly diagnosed GGM despite published phase III data and regulatory approval, and only 30% viewed TTF as definitively part of the standard of care treatment. A majority (87%) opposed mandating TTF incorporation into the design of clinical trials.

Conclusions: Providers continue to view TTF with some level of skepticism, with a lack of additional supportive data and logistical concerns representing continued barriers to uptake.