Feasibility evaluation of tumor treating fields for brainstem gliomas

Clinical Snapshot

Key Findings

• P Value: GTV: p=0.019; CTV: p=0.002; Brainstem: p=0.002; Posterior fossa: p<0.001; LMiPD all regions: p≤0.006

• Effect Size: GTV: optimised 1.1 V/cm vs. standard 1.0 V/cm; CTV: 1.1 vs. 1.0 V/cm; Brainstem: 1.3 vs. 1.1 V/cm; Posterior fossa: 1.5 vs. 1.2 V/cm (all median values)

• Primary Outcome: Local minimum field intensity (LMiFI) within GTV, CTV, brainstem, and posterior fossa comparing MAXPOINT®-optimised versus standard unplanned transducer array layouts

• Nnt Or Sensitivity: Not applicable (simulation study; no clinical event rates reported). All optimised layouts met the ≥1.0 V/cm therapeutic reference threshold.

• Confidence Interval: Not reported

Clinical Application

Clinical implementation remains premature. The simulation demonstrates theoretical dosimetric feasibility only. Prospective clinical trials with safety monitoring, tolerability assessment, and survival endpoints are required before TTFields can be considered for brainstem gliomas outside a research protocol. Scalp-only array placement is a practical advantage over arrays requiring posterior fossa positioning. TTFields (Optune®, Novocure) is not TGA-approved for brainstem gliomas and is not listed on the PBS for any indication in Australia. For supratentorial GBM, access in Australia is limited to private funding or clinical trials. RACGP and COSA guidelines do not currently include TTFields for infratentorial tumours. Australian neuro-oncologists considering this modality for brainstem gliomas would need to do so within an ethics-approved clinical trial framework. The cost of TTFields devices (approximately AUD $20,000–$25,000/month internationally) represents a significant barrier to access in the Australian public health system. Adult patients with brainstem gliomas (diffuse intrinsic pontine glioma or other brainstem glioma subtypes) being considered for novel or adjunctive therapies. The simulation data are most relevant to neuro-oncology centres exploring TTFields as an investigational modality for infratentorial disease.

Abstract

PURPOSE: Tumor treating fields (TTFields) are FDA-approved for supratentorial glioblastoma, but feasibility in infratentorial tumors remains poorly defined. This simulation study evaluated TTFields dose in brainstem gliomas using patient-specific modeling with scalp-only transducer arrays. METHODS: MRI and CT imaging from seven patients with brainstem gliomas were used for TTFields planning with MAXPOINT® (Novocure, Switzerland). Clinical target volume (CTV) was defined as enhancing tumor on T1 post-contrast MRI (Gross tumor volume, GTV) plus a 3 mm peritumoral expansion. The platform optimized scalp-only array layouts, and finite element calculations generated maps of local minimum field intensity (LMiFI, V/cm) and local minimum power density (LMiPD, mW/cm³). Values were compared against a standard, unplanned layout using one-sided paired t-tests, with LMiFI ≥ 1.0 V/cm as a therapeutic reference. RESULTS: MAXPOINT-optimized layouts achieved significantly higher LMiFI than the standard layout across all regions (all p ≤ 0.019). GTV median LMiFI was 1.1 vs. 1.0 V/cm (p = 0.019). CTV median LMiFI was 1.1 vs. 1.0 V/cm (p = 0.002). Brainstem median LMiFI was 1.3 vs. 1.1 V/cm (p = 0.002). Posterior fossa showed the largest difference: median LMiFI 1.5 vs. 1.2 V/cm (p < 0.001). All optimized LMiFI values met or exceeded the therapeutic reference. LMiPD was also significantly higher with MAXPOINT® across all regions (all p ≤ 0.006). CONCLUSION: This simulation study demonstrates that patient-specific modeling can achieve favorable TTFields intensities in brainstem gliomas using scalp-only arrays, supporting prospective clinical evaluation for infratentorial tumors.

References

1. 1.Chen, A. Y., Shah, R., Shi, W., Urman, N., Shapira, N., Avgeropoulos, N., Conlon, P., Mookerjee, N., & Shi, W. (2026). Feasibility evaluation of tumor treating fields for brainstem gliomas. Journal of Neuro-Oncology. https://doi.org/10.3390/children13010084