Thermal Therapy Approaches for Treatment of Brain Tumors in Animals and Humans

Abstract

Primary brain tumors are often aggressive, with short survival from time of diagnosis even with standard of care therapies such as surgery, chemotherapy, and radiation therapy. Thermal therapies have been extensively investigated as both primary and adjuvant therapy. Although thermal therapies are not yet widely used clinically, there have been several promising approaches demonstrated in both animals and humans. This review presents thermal therapy approaches in animal and human studies, including both hyperthermia (temperatures ~42°C–45°C) and thermal ablation (temperatures > 50°C). Hyperthermia is primarily used as adjuvant to chemotherapy and radiotherapy, and is the most widely studied radiation sensitizer where enhanced efficacy has been shown in human patients with brain cancer. Hyperthermia has additional beneficial effects such as immunogenic effects, and opening of the blood-brain barrier to potentially enhance drug delivery, for example in combination with nanoparticle drug delivery systems. Thermal ablation uses high temperatures for direct local tumor destruction, and it found its way into clinical use as laser interstitial thermal therapy (LITT). This review presents various hyperthermia and ablation approaches, including a review of different devices and methods that have been used for thermal therapies, such as radiofrequency/microwaves, laser, high-intensity focused ultrasound, and magnetic nanoparticles. Current research efforts include the combination of advanced thermal therapy devices, such as focused ultrasound with radiation, as well as the use of thermal therapies to enhance chemotherapy delivery across the blood-brain barrier.

Heating technology for malignant tumors: a review

“…Laser Interstitial Thermal Therapy (LITT) uses laser light transmitted by an optical fiber which is converted into thermal energy and damages tissue in the target volume. The probe is often cooled to prevent tissue vaporization due to excessively high temperatures near the applicator [258]. An advantage of LITT is that it allows more accurate and safer ablation near critical structures than radiofrequency and microwave ablation.…”

Ablative brain surgery: an overview

“…The standard of care therapy for most primary and secondary brain tumors consists of a combination of resective surgery, chemotherapy and/or radiation therapy. Over time, these standard treatments have been complemented by several thermal and nonthermal ablative procedures [9,154].…”

“…Among electromagnetic wave energies, both RF and microwaves have been delivered through interstitial applicators for the thermal ablation of brain tumors [154,156]. These techniques were used for the management of deep-seated and/or critically located lesions, and they were coupled with MRI guidance so as to safely and accurately reach the planned intracranial targets [158].…”

<p>Development of anisamide-targeted PEGylated gold nanorods to deliver epirubicin for chemo-photothermal therapy in tumor-bearing mice</p>

“…EPI formulation (Figures 6 and S6). It has been reported that thermal therapy (also called hyperthermia) may increase the sensitivity of cancer cells to DOX and EPI, 50 as hyperthermia can retard the repair of DNA damage caused by anthracycline antibiotics. 51 Indeed, when stimulated with β Figure 6 The expression of caspase 3, cleaved caspase 3 (phosphorylated form), caspase 9, cleaved caspase 9 (phosphorylated form), Bcl-2, Bax, and β-actin was determined using Western blotting.…”