Modelling of the electrochemial treatment of tumours

Sammanfattning: The electrochemical treatment (EChT) of tumours entails thattumour tissue is treated with a continuous direct currentthrough two or more electrodes placed in or near the tumour.Promising results have been reported from clinical trials inChina, where more than ten thousand patients have been treatedwith EChT during the past ten years. Before clinical trials canbe conducted outside of China, the underlying destructionmechanism behind EChT must be clarified and a reliabledose-planning strategy has to be developed. One approach inachieving this is through mathematical modelling.Mathematical models, describing the physicochemical reactionand transport processes of species dissolved in tissuesurrounding platinum anodes and cathodes, during EChT, aredeveloped and visualised in this thesis. The consideredelectrochemical reactions are oxygen and chlorine evolution, atthe anode, and hydrogen evolution at the cathode. Concentrationprofiles of substances dissolved in tissue, and the potentialprofile within the tissue itself, are simulated as functions oftime. In addition to the modelling work, the thesis includes anexperimental EChT study on healthy mammary tissue in rats. Theresults from the experimental study enable an investigation ofthe validity of the mathematical models, as well as of theirapplicability for dose planning.The studies presented in this thesis have given a strongindication of the destruction mechanism involved in EChT. It isshown by the modelling work, in combination with theexperiments, that the most probable cause of tissue destructionis acidification at the anode and alkalisation at the cathode.The pH profiles obtained from the theoretical models have showngood correlation with the experimentally measured destructionzones, assuming that a pH above and below certain values causetissue destruction. This implies that the models presented inthis thesis could be of use in predicting the tumourdestruction produced through EChT, and thereby provide a basisfor a systematic dose planning of clinical treatments.Moreover, the models can serve as valuable tools in optimisingthe operating conditions of EChT.Modelling work of theanode processes has explained the roleof chlorine in the underlying destruction mechanism behindEChT. It is found that the reactions of chlorine with tissueplay important roles as generators of hydrogen ions. Thecontribution of these reactions to the acidification of tissue,surrounding the anode, is strongly dependent on the appliedcurrent density and increases with decreasing currentdensity.Keywords:cancer, direct current, dose planning,electrochemical treatment (EChT), electrotherapy, mathematicalmodelling, tumour.