Rthp-13. Tumor-treating Fields Therapy Is Compatible With Standard Chemoradiotherapy for Glioblastoma
Year: 2018
Type: conference-abstract
Abstract: PURPOSE: The phase III EF-14 trial demonstrated a significant overall survival benefit in 695 patients with glioblastoma who received adjuvant anti-mitotic tumor-treating fields (TTFields) therapy in addition to temozolomide (TMZ), following standard concurrent radiotherapy (RT) and TMZ. Preclinical studies suggest that there may be an added synergistic benefit to TTFields when used concurrently with RT. We therefore conducted dosimetric analyses to assess whether the presence and repositioning of TTFields scalp arrays interferes with RT delivery and to evaluate implications for treatment planning. RT plans from ten consecutive glioblastoma patients at our institution were transferred to an anthropomorphic cranial phantom and re-optimized using standard tumor and normal tissue constraints. Optimized plans were then copied to CT scans of the phantom wearing the TTFields array in three discrete positions, to simulate routine replacement of the array in clinical use. Individual and average perturbations to RT dosimetry for each plan/array combination were then analyzed. The percent change in planning target volume (PTV) coverage for each of the 30 combinations ranged from -3.0% to 1.1%. When averaged over the three array positions, PTV coverage for each patient had standard deviation of less than 1.0%. Changes in PTV coverage were attributable to attenuation by the array and increased superficial dose owing to bolus effect. Percent increase in radiation dose to skin was 5.0% or less in 9 out of 10 plans. The dosimetric impact of the TTFields arrays for any individual position is small and is further mitigated by repositioning of the arrays as would occur during chemoradiation. These dosimetric changes were consistent across varied tumor location, laterality, and RT beam arrangement in our patient cohort. We are initiating a clinical trial to test safety and develop procedures for the use of TTFields during chemoradiotherapy for glioblastoma.
Source: Neuro-Oncology
Language: English
Subfield: Radiation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2899631290