Biochemical and Metabolomic Changes after Electromagnetic Hyperthermia Exposure to Treat Colorectal Cancer Liver Implants in Rats

Background: Hyperthermia (HT) therapy still remains relatively unknown, in terms of both its biological and therapeutic effects. This work aims to analyze the effects of exposure to HT, such as that required in anti-tumor magnetic hyperthermia therapies, using metabolomic and serum parameters routinely analyzed in clinical practice. Methods: WAG/RigHsd rats were assigned to the different experimental groups needed to emulate all of the procedures involved in the treatment of liver metastases by HT. Twelve hours or ten days after the electromagnetic HT (606 kHz and 14 kA/m during 21 min), blood samples were retrieved and liver samples were obtained. 1H-nuclear-magnetic-resonance spectroscopy (1H-NMR) was used to search for possible diagnostic biomarkers of HT effects on the rat liver tissue. All of the data obtained from the hydrophilic fraction of the tissues were analyzed and modeled using chemometric tools. Results: Hepatic enzyme levels were significantly increased in animals that underwent hyperthermia after 12 h, but 10 d later they could not be detected anymore. The metabolomic profile (main metabolic differences were found in phosphatidylcholine, taurine, glucose, lactate and pyruvate, among others) also showed that the therapy significantly altered metabolism in the liver within 12 h (with two different patterns); however, those changes reverted to a control-profile pattern after 10 days. Conclusions: Magnetic hyperthermia could be considered as a safe therapy to treat liver metastases, since it does not induce irreversible physiological changes after application.

Hyperthermia for deep seated tumours – possibilities of heating with capacitive devices

The review examines the general principles of capacitive electromagnetic hyperthermia (EMHT), the distribution of electromagnetic energy in various experimental models and in patients’ tumors, the design features of applicators from various capacitive hyperthermic systems and their role in achieving hyperthermic mode in tumors of deep localization. In classical capacitive EMHT, the main obstacle in achieving the required temperature in such tumors is overheating of the subcutaneous fatty tissue under the electrodes. For some capacitive hyperthermic systems, the heating of adipose tissues is enhanced due to the fact that the applicator design does not conform to certain technical requirements. In capacitive EMHT at frequencies of 8–13.56 MHz, obtaining the minimum hyperthermic mode is possible with output powers of 500–800 W, maximum – 1000–1200 W and above. The results of the use of various hyperthermic capacitive systems in patients with malignant tumors of internal organs are analyzed.

Heating Effects of the Magnetic-Nanoparticle Enhanced Hyperthermia Targeting Tumors Underneath the Ribs

Aiming at providing a detailed disclosure on the thermal effects of EM (electromagnetic) hyperthermia on the liver tumor underneath the ribs, this paper has numerically provided comprehensive interpretations on the heating effects of magnetic nano-particles induced hyperthermia for target tumor treatment. The results revealed the following factors: (1) The existing of bone structure, i.e. ribs has an inevitable effect on the distribution of EM field; specifically, due to its lower dielectric property, the bone structure seemingly acts as a barrier to attenuate the access of EM energy into the tissue, especially the tumor in the deep body. (2) Using higher dosage or bigger size magnetic nano-particles have greatly enhanced the temperature elevation of targeted tumor tissue and thereby obtain good performance of hyperthermia. (3) Further parametric studies indicated that a worse heating effect would be obtained when utilizing external EM field with a higher frequency of 10MHz; while higher strength of EM field would evidently enhance the heating effects of such EM hyperthermia. The present study would promote the understandings of thermal effects on the specific organs in EM hyperthermia, and the findings are expected to provide valuable guidance for planning an accurate dosage in clinical liver tumor thermal ablation.