Tumor treatment by direct electric current-tumor temperature and pH, electrode material and configuration

Electrotherapy with low-level direct current has been suggested as an effective regional cancer treatment. A great variety of electrode materials, their placement with respect to tumor (i.e. electrode configurations) current levels and therapeutic schedules have been employed to date. In our paper the impact of electrode materials and configurations was studied, employing the same treatment parameters and schedule, on the subcutaneously grown solid tumor fibrosarcoma SA-I in A/I mice. The effect of electrotherapy was assessed by tumor volume determination on each consecutive day and by determination of the extent of necrosis along the tumor's greatest diameter immediately after electrotherapy, 24, 48 and 72 hours later. The development of tumor necrosis after electrotherapy application differed for different electrode configurations. Intratumoral temperature and pH were measured before and after the application of electrotherapy in all electrode configurations used. Irrespective of the electrode configuration the intratumoral temperature was unchanged by electrotherapy. Considerable variations in pH were revealed for configurations where one electrode was inserted into the tumor, whereas in configurations with both electrodes outside, the tumor pH remained unchanged by electrotherapy. Electrodes made of platinum, platinum (90%): iridium (10%) alloy, gold, silver and titanium were used for current delivery, and significant tumor growth retardation was achieved irrespective of electrode configuration and material (p < 0.001, Mann-Whitney Rank-Sum test}. In addition to possible toxicity arising from dissolved metal ions and products of electrochemical reactions, which may result from electrolysis, direct effects of current on tumor and immune cells are suggested . • To whom correspondence should be addressed. 0302-4598/93/$06.00 © 1993 Elsevier Sequoia S.A. All rights reserved