Background: Local antitumoral therapy of metastases is an important tool in the palliative treatment of advanced colorectal cancer. Several authors have recently reported on successful local treatment of different malignant diseases with low-level direct current therapy. The aim of the present study was to compare the effectiveness of direct current therapy with the established laser-induced thermotherapy (LITT) on experimental colorectal liver metastases.
Materials and methods: Colorectal metastases were induced in 49 BD IX rats by injection of colon cancer cells beneath the liver capsule. Three weeks after induction, tumor volumes and sizes were estimated with magnetic resonance imaging and by manual measurement of the largest tumor diameter, and two treatment groups and two control groups were established. Direct current (80 C/cm(3)) versus LITT (2 W; 5 to 10 min) was locally applied via laparotomy. Control groups were sham treated. Tumor growth was analyzed 5 wk after therapy by manual measurement of the maximal diameter and histopathological examination was performed.
Results: Measurement of tumor sizes 5 wk after therapy confirmed a significant antitumoral effect of direct current (1.6-fold tumor enlargement) and of LITT (1.3-fold tumor enlargement), compared with controls (2.8-fold and 2.9-fold tumor enlargement). However, after 5 wk, LITT was significantly more effective in limiting tumor growth than direct current treatment (P </= 0,001). Histopathological analysis revealed a complete response rate of 21% and a partial response rate of 77% in the electric current group. In comparison, LITT treated livers showed a complete response rate of 22% and a partial response rate of 78% (n.s.).
Conclusions: The data confirm that direct current therapy and LITT are effective treatment strategies in the palliative control of colorectal hepatic metastases, with both therapies being equally effective in inducing a complete or partial tumor necrosis.