Several authors recently reported on the successful local treatment of malignant disease with low-level direct current therapy. However, antitumoral effects in colorectal metastases has not been investigated experimentally. The aim of the present study was to assess the effectiveness of this therapy and the influence of polarity and current dose. Colorectal metastases were established in BD IX rats by the injection of colon cancer cells under the liver capsule. After three weeks, the liver tumor volumes were determined by magnetic resonance imaging of the liver. Low-level direct current therapy was applied via five platinum electrodes. Four different applications were used: 60 C/cm(3), anode at the center; 60 C/cm(3), cathode at the center; 80 C/cm(3), anode at the center; and 80 C/cm(3), cathode at the center. In the control group, five electrodes were placed without applying any direct current. All animals were sacrificed on postoperative day 7. Liver metastases were histologically examined for vital tumor cells. Statistical analysis was performed with chi(2)-test. The mean initial tumor diameter before treatment was 3.6 +/- 1.4 mm (volume: 25.2 +/- 9.7 mm(3)). Histological examination of the removed livers revealed significant destruction of the metastases with localized necroses in all treatment groups; 37% had a complete response rate and 63% a partial response rate. There were no significant necroses in the control group (P < 0.0001). The best treatment results were obtained in the group with an anode at the center and a current dose of 80 C/cm(3). Direct current therapy offers a new and safe method for the local treatment of liver metastases. We were able to observe that tumor damage is related to current dose but not to the polarity of the central electrode.
Copyright 2000 Wiley-Liss, Inc.