TREATMENT OF HEPATIC METASTASES OF COLORECTAL-CANCER BY ELECTROCHEMOTHERAPY - AN EXPERIMENTAL-STUDY IN THE RAT

Background. Electrochemotherapy, which consists of local or systemic a dministration of a cytotoxic agent followed by application of electric pulses to a tumor, has proved effective for various types of tumors i n animals and for cutaneous and head and neck cancers in human beings. This is the first study to investigate the efficacy of electrochemoth erapy for treatment of hepatic metastases of colorectal cancer in the rat. Methods. After induction of a solitary hepatic metastasis in 36 m ale BDIX rats, the animals were randomized to one of four groups: B-E- (no treatment), B+E- (intratumoral bleomycin), B-E+ (application of e lectric pulses to the tumor), and B+E+ (electrochemotherapy: intratumo ral bleomycin followed by application of electric pulses). Results. Gr oups B-E- and B-E+ had no tumor response. Group B+E- had one partial r esponse. Group B+E+ had seven partial responses and two complete respo nses. The difference in terms of response between group B+E+ and the o ther three groups was statistically significant (P <.05). comparison o f the mean posttherapy tumor volumes (B-E-, 50.6 mm(3) B+E-, 58.7 mm(3 ); B-E+, 46 mm(3); and B+E+ 5.65 mm(3)) revealed a significantly small er residual tumor in group B+E+ than in the other three groups (P < .0 5). Conclusions. Electrochemotherapy is an effective means to reduce t he volume of hepatic metastases of colorectal cancer in the rat. Addit ional research is required to determine the optimum treatment duration , dose effects, volume of tumor that can be treated by electrochemothe rapy, and impact on survival. Such experimental studies are indispensa ble prerequisites for clinical trials.