The data at the right show the typical proliferation responses for cancer cells and normal cells that have been reported by O'Clock; Lyte, Gannon and O'Clock and O'Clock and Leonard since 1991. Of the different cancer cells evaluated so far (EL-4 lymphoma cells, leukemia cells, IL-6 hybridoma melanocytes and retinoblastoma cells), all of these malignant cancer cells exhibit the same "window" of suppression as indicated by the proliferation response characteristics for malignant retinoblastoma cells (top). The normal retinal cells response is shown at the bottom. Malignant cell proliferation is severely repressed by electrical current levels within the "window" of proliferation suppression. Generally, normal cells are not as severely suppressed at these current levels. In fact, as the graph indicates, some normal cell proliferation characteristics show indications of enhancement at the current levels that tend to suppress malignant cells. This is a very important advantage for therapeutic applications.
What is interesting is that, considering all of the malignant cells tested in vitro, the calculated current densities within the "window" of malignant cell proliferation suppression, are in the range of 900 µA/centimeter squared to 1,800 µA/centimeter squared. These are the same levels of current density that produced necrobiosis in the in vivo/in vitro studies of tissues and cells by Ito and O'Clock and Leonard.
One might ask how these results relate to EChT clinical studies. In order to answer this kind of question, Thomasset's work must be considered(see previous pages, Biophysics of BCEC). Data provided by Thomasset indicate that the impedance of malignant tissues is in excess of 2,500 ohms, and may be closer to 5,000 ohms. However, the clinical EChT data provided by Dr. Xin, Yu Ling indicates that, for EChT, applied voltages of 6 V to 10 V yield currents of 40 mA to 120mA (10 mA to 30 mA per electrode pair). With approximately 75% of the applied voltage dropped accross the the electrode tissue interface, and using Ohm's law, these EChT voltages and currents indicate overall tumor impedances of approximately 22 ohms to 30 ohms with individual tumor impedance levels between each electrode pair (assuming 4 electrode pairs) of 90 ohms to 120 ohms.
The reason that the impedance for the actual tumor structure is much smaller than the measured impedance for tumor tissues appears to be due to the fact that; as electrodes are inserted into the tumor tissue, they come into contact with the tumor's vascular system, fluids and fluid matrix regions. Most of the EChT current appears to be shunted by body fluids and other tissues. Since the tumor structure impedance is approximately 2% to 4% of the 2,500 ohm to 5,000 ohm impedance of the cancer tissue, the tissue is only receiving approximately 2% to 4% of the current delivered. If 10 mA to 30 mA of electrical current per electrode pair is being delivered to the tumor, due to the relatively high impedance level of cancer tissue, the cancer tissue and cancer cells are only being influenced by approximately 2% to 4% of the total EChT current level. In this case, for an electrode pair, the cancer tissue and cancer cells are actually being influenced by currents in the range of 200 µA to 1,200 µA. For each electrode pair inserted 1 cm. into a tumor, the cross sectional area of the tumor region excited by the thin electrodes could be as high as 0.5 centimeter squared. For cancer patients receiving EChT treatment, this would yield electrotherapeutic current densities in the range of 400 µA/centimeter squared to 2,400 µA/centimeter squared.
Comments by Dr. Xin, Yu Ling indicated more favorable responses at lower EChT currents, or lower EChT current density levels. The current density levels that produced necrobiosis and apoptosis in the Ito and O'Clock and Leonard papers strongly indicate that lower levels of EChT current density may be more effective from the standpoint of attacking the individual cancer cells.
In conclusion, it is remarkable that, from the standpoint of the current densities that are the most effective with respect to promoting tumor regression, tumor structural component damage, apoptosis in malignant cells and malignant cell necrosis; the in vivo, in vitro and EChT clinical studies all point toward the same range of current densities as being optimum, producing the best results with respect to mitigating the cancer condition.
From: M. Lyte, J.E. Gannon and G.D. O'Clock, Journal of the National Cancer Institute, Vol. 83, January 16, 1991; C.K. Chou, et.al., Bioelectromagnetics, Vol. 18, 1997; Y. Yen, et.al., Bioelectromagnetics, Vol. 20, 1999; G.D. O'Clock and T. Leonard, German Journal of Oncology, Vol. 33, 2001; Ito, et.al., Journal of the IABC, Vol. 1, January-December, 2002; Y.L. Xin, et.al., Journal of the IABC, Vol. 1, January-December, 2002; G.D. O'Clock, Electrotherapeutic Devices: Principles, Design and Applications, Artech House, Boston, MA (2007).