Purpose: Evaluation of the efficacy of direct current and laser therapy in the treatment of colorectal liver metastases in a rat model.
Materials and methods: Liver metastases in 49 rats were induced by subcapsular injection of cells of a colorectal tumor cell line. 3 weeks after inoculation 41 tumors were treated by laser and 56 tumors by direct current therapy. 17 tumors served as a control in the direct current group, 12 in the laser therapy group. The inoculation rate and the tumor size 3 and 5 weeks after therapy were determined by MRI.
Results: The MR-tomographically determined inoculation rate was 133 tumors after 151 tumor cell injections (88%). Three and five weeks after laser therapy, tumor growth rates of 15% and 18% were documented (maximum tumor diameter). This represented a significant reduction in growth (p < or = 0.01 and p < or = 0.001) compared to the control group (growth rate 230% and 280%). In the direct current therapy group, growth rates were 40% after 3 and 60% after 5 weeks. Compared to the control group (210% and 290%), this also represented a significant reduction (p < or = 0.001).
Conclusions: This animal study is the first to demonstrate an antitumor effect of direct-current therapy on liver metastases of colorectal cancer in rats. Nevertheless, the laser therapy proved to be more effective.