A. Mokthare, S.K. Reddy, E.P. Furlani
University at Buffalo,
Keywords: electrochemical therapy (EChT), tumor electrolysis, tumor destruction, mathematical modelling, non-buffered and buffered models, Nernst-Planck equations
Summary:Electrochemical therapy (EChT) is a promising alternative to conventional tumor treatment due to its relatively high efficiency, flexibility, reduced side effects and versatility. Tumor electrolysis, a form of EChT, utilizes low-level direct electric current (DEC). Electrolysis creates acidic and alkaline zones around anodic and cathodic implant electrodes that contribute to tissue necrosis. Determining the optimum current density distribution to apply when using different electrode arrays is one of the most important challenges to improve the efficacy of EChT. While the development of EChTs has been an active research area for the last three decades, relatively few rigorous process models exist and rational design is lacking. In this presentation we introduce two different numerical models of EChT, non-buffered and buffered models. We demonstrate the models for a configuration of positive and negative straight and opposing electrodes in tumor tissue, which is modeled as an aqueous solution of saline bicarbonate buffer system with or without organic constituents. The model simulates the EChT process in a two-dimensional (2D) axisymmetric environment. A finite element analysis (FEA) package, COMSOL Multiphysics 5.3® was used for solving Tertiary Current Distribution, Nernst-Planck equations. We found that depending on the tissue geometry, suitable current densities and treatment duration might range from approximately 5 to 100 mA/cm2, and from 10 to 15 minutes respectively. Our simulations predict that an initial condition with a homogeneous and almost neutral pH becomes extremely acidic (pH 2–3) and extremely basic (pH 10–12) in vicinity of the anode and cathode, respectively. Concentration profiles of sodium, chloride, bicarbonate, carbonate, organic buffer pair, after 15 minutes of the EChT and the electrolyte potential distribution, as a function of time, are calculated. Our analysis shows a good correlation of pH and destruction zone at higher currents obtained around the electrodes. The simulation results are consistent with the experimentally measured lesions, thus indicating that it is the spreading of hydroxyl and hydrogen ions that determines the extent of tissue destruction around the cathode and anode respectively. This approach and results open a promising area of research that may help in the interpretation of the real consequences of an EChT applied to tumor tissues. We believe this could have significant implications in the future design of optimal operative conditions and dose planning of this kind of therapy.