Temperature and Impedance Variations During Tumor Treating Fields (TTFields) Treatment

Abstract

Tumor Treating Fields (TTFields) is an FDA-approved cancer treatment technique used for glioblastoma multiforme (GBM). It consists in the application of alternating (100–500 kHz) and low-intensity (1–3 V/cm) electric fields (EFs) to interfere with the mitotic process of tumoral cells. In patients, these fields are applied via transducer arrays strategically positioned on the scalp using the NovoTAL™ system. It is recommended that the patient stays under the application of these fields for as long as possible. Inevitably, the temperature of the scalp increases because of the Joule effect, and it will remain above basal values for most part of the day. Furthermore, it is also known that the impedance of the head changes throughout treatment and that it might also play a role in the temperature variations. The goals of this work were to investigate how to realistically account for these increases and to quantify their impact in the choice of optimal arrays positions using a realistic head model with arrays positions obtained through NovoTAL™. We also studied the impedance variations based on the log files of patients who participated in the EF-14 clinical trial. Our computational results indicated that the layouts in which the arrays were very close to each other led to the appearance of a temperature hotspot that limited how much current could be injected which could consequently reduce treatment efficacy. Based on these data, we suggest that the arrays should be placed at least 1 cm apart from each other. The analysis of the impedance showed that the variations seen during treatment could be explained by three main factors: slow and long-term variations, array placement, and circadian rhythm. Our work indicates that both the temperature and impedance variations should be accounted for to improve the accuracy of computational results when investigating TTFields.

Saikosaponin D Inducing Apoptosis and Autophagy through the Activation of Endoplasmic Reticulum Stress in Glioblastoma

“…Over the past 30 years, the survival rates of patients with GBM have shown only slight improvement. Currently, temozolomide [ 20 ] and tumor treatment field (TTF) [ 21 ] are used to treat GBM. Noninvasive devices from Novocure GmbH have demonstrated clinical efficacy and improved results.…”

Electric field distributions in realistic 3D rat head models during alternating electric field (AEF) therapy: a computational study

“…AEFs) on biological tissues, as well as optimizing the patient-specific treatment (Wenger et al 2015b, Korshoej et al 2017. AEF therapy outcome was also predicted by simulating the electric field strength/intensity delivered to the viable tumor (Ballo et al 2019), referred to here as the 'active shell' (Wenger et al 2016, Gentilal et al 2022. To produce accurate results, simulations require knowledge about the electric properties of individual tissues.…”