Use of radiofrequency electromagnetic fields applied by capacitive hyperthermia for glioblastoma therapy

Abstract

Introduction: Radiofrequency electromagnetic fields applied by capacitive hyperthermia (cRF-HT) might be applicable to improve therapy for glioblastoma patients, but computer simulation data is scarce. We aimed to perform a numerical analysis of cRF-HT treatment in glioblastoma patients.

Methods: The EHY-2030 cRF-HT system (Oncotherm, Budapest, Hungary) was studied using a round 20 cm diameter electrode. Realistic head models and quasi-electrostatic finite element simulations were created (Sim4Life v7.2, ZurichMedTech, Zürich, Switzerland). First, 109 spherical glioblastoma localizations were created within a healthy head model, and three different electrode setups were used to simulate the specific absorption rate (SAR). Then, in 20 real glioblastoma patients, the E-field and SAR in the gross tumor volume (GTV) and its boundary zone were simulated, and transient temperature simulations were performed.

Results: The simulations conducted on 20 patients revealed that the SAR achieved in the GTV and its surrounding boundary zone is highly dependent on the localization of the tumor, with a mean SAR of 24.3 W/kg (ranging from 11.5 to 46.7 W/kg). The mean temperature within the GTV was higher in patients with a resection cavity (mean T₅₀: 40.1 °C) instead of a macroscopic tumor (mean T₅₀: 37.8 °C). The simulation outcome for the 109 artificial tumor localizations indicated enhanced effectiveness when the electrode is setup as close to the GTV as possible.

Conclusion: cRF-HT may induce mild hyperthermia in a subgroup of glioblastoma patients with resection cavities. In macroscopic tumors, temperatures remain below the hyperthermia threshold. Further research is required to assess the clinical benefit of this therapy.

Keywords: Capacitive hyperthermia; amplitude–modulation; glioblastoma; non–thermal effects; simulation; treatment planning.