The Electrochemotherapy (ECT) is an effective treatment of cutaneous and subcutaneous solid tumors. Electric field is applied to tumor nodules to enhance the delivery/distribution of a non-permeable or poorly permeable chemotherapeutic agent into the tumor cells thereby increasing local concentration of anticancer drugs. The aim of this study was to evaluate the effectiveness of using two types of electric fields in ECT, pulsed sine waves and direct current (DC) application in addition to intra-tumoral injection of bleomycin (BLM), a cytotoxic drug for treating Ehrlich tumor. The electric fields were delivered through six stainless steel needle electrodes inserted into the tumor. Tumor volume, tumor mass, percentage of fragmented DNA in the tumor tissue, relative spleen mass/total body mass, mortality rate, histological and ultrastructural examinations were investigated in each group. There were 40% complete response (CR) and 60% partial response (PR) in the group treated with DC as the electric field source of ECT, while 0% (CR) and only 25% (PR) were found in the group treated with pulsed sine wave ECT. We concluded that the utilization of low dose DC for ECT gives better results than the low voltage pulsed sine waves in treating Ehrlich tumor which may be due to the dual effects of electrochemical reactions evoked by DC application and the anti-cancer activity of BLM.
Keywords: bleomycin; direct current; electrochemotherapy; low electric field.