Why & How
Medical Device Details
Oncotherm EHY2000 & EHY2030
Mechanism of Action
Modulated electro-hyperthermia (mEHT; trade name: oncothermia) is a relatively new method of hyperthermia proposed by Szasz et al. which differs from conventional heating methods in that it focusses on the selective heating of the extracellular matrix and cell membranes in the malignant tissuerather than on the homogenous heating goal of conventional heating techniques. Technically, mEHT is a precious impedance matched the capacitive coupled device.
The mEHT technique is based on two principles: it replaces the single temperature concept that was used previously in hyperthermia with energy that is measured in (kJ/kg), returning the technique to the gold standard dose concepts known to radiation oncologists; it selectively delivers this energy into the tumor without affecting the healthy neighbouring tissue. To successfully target tumor cells, the modified metabolic and biophysical conditions of cancer cells allow for selective targeting of the energy. In contrast to normal cells, cancer cells rely mainly on anaerobic glycolysis, regardless of oxygen availability. This phenomenon is known as the “Warburg effect”. The fermentation of glucose by cancer cells results in the production of two ATP molecules rather than the 36 ATP molecules that result from the complete oxidation of glucose in the mitochondria of healthy cells. Many applications take advantage of this fundamental difference, such as positron emission tomography (PET) diagnosis. As a result of the increased glucose uptake, the lactic acid production increases, and other metabolites contribute to a higher proliferation rate in the microenvironment of the cancer cells. The subsequently decreased extracellular pH and “reversed” intracellular pH also help identify the cancer cells.
The basic metabolic differences between cancer and noncancer cells make their electrical recognition possible and include the following characteristics:
-The ability of cancer cells to produce sufficient ATP is low. A large amount of ATP is needed for proliferative energy consumption. Cancer has less ATP for active membrane stabilization by K+ and Na+ transport; thus, the membrane potentiation weakens
– The cellular membrane of cancerous cells is electrochemically different from normal cells, since they are negatively charged on average.
The composition of membrane lipids and sterols differs dramatically between cancer cells and normal healthy cells.
As a result of these differences, the membrane permeability of cancer cells is altered. Thus, the efflux of K+, Mg2+, and Ca2+ ions increases, whereas the efflux of Na+ and water transport from the cell decreases. Accordingly, the cell swells, which causes an additional reduction in its membrane potential. Furthermore, as the network of cellular connections (cadherins and junctions) are broken, the cancer cells become autonomic, changing the dielectric properties (growing the dielectric permeability) of the microenvironment, while the resistance decreases. All of these factors contribute to the negative polarization of the tumor and an increase in its conductivity, which is used in electrochemical cancer therapy.
Selection Based on the Tissue
Modulated RF is applied (13.56 MHz)
– Patient and tumour forms part of an electric circuit.
– Higher ion concentration in tumour = lower impedance
– Applied electric field moves through tumour more readily
– Excites the electrons in the extracellular matrix = heat