Tumor-Treating Electric Fields for Glioblastoma

Historical context of electric field treatment

The application of physical energy from various parts of the electromagnetic spectrum is common in glioblastoma treatment. The most widely used involves energies from the higher end of the spectrum in exahertz (the 10 ¹⁸ -Hz range), in which ionizing radiation is used to treat various types of malignancies, including glioblastoma ( Fig. 17.1 ). Therapeutic radiation can be diffuse, as in whole-brain and involved-field radiotherapy, or highly conformal, as in stereotactic radiosurgery (SRS), and the biological responses to these different types of radiation are different, as modeled by the linear-quadratic dose-effect relationship. At the lower end of the spectrum, in the gigahertz or 10 ⁹ -Hz microwave range, laser interstitial thermal therapy (LITT) is being used for the thermocoagulation of brain tumors and the treatment of radiation necrosis. MRI technology now allows the real-time visualization of temperature changes during LITT treatment of a target lesion. In addition, at an even lower part of the electromagnetic spectrum, in the kilohertz or 10 ³ -Hz range, alternating electric field therapy or tumor-treating electric fields (TTFields) are now an established treatment for glioblastoma. This chapter provides a summary of the cell biology and physical science effects of TTFields on tumor cells and tumors in the brain, as well as a historical perspective of the clinical studies conducted in the glioblastoma population.

Biological basis and physical science supporting the use of tumor-treating electric fields