The antitumor activity of direct current was studied in mice which were transplanted
fibrosarcoma (FSa) into the right thigh. Mice were inserted
electrodes into
tumor and normal tissue surrounding the
tumor, and treated with constant current. The direct current
therapy (D.C.T.) (0.6 mA, 120 min) alone was effective to regress
tumor, but
tumor was not eradicated by D.C.T. alone.
Cyclophosphamide (CPA, 100 mg/kg) could markedly reduce the FSa
tumor size, but all
tumor regrew finally. When D.C.T. was combined with CPA (100 mg/kg), the therapeutic response of FSa
tumor was enhanced in mice which were inserted cathode into
tumor. For example, in mice receiving direct current (0.6 mA, 120 minutes), the cure rate was 70% compared with 30% by the
anode in
tumor. Using cure rate assay, D.C.T. and about half dose of CPA could give the similar treatment results as the full dose of CPA alone. That is, D.C.T. will be able to reduce the dose of chemotherapeutic agents. Combination of D.C.T. and
doxorubicin was not so effective as CPA, but showed the similar results. The experimental results suggest that D.C.T. alters the
drug distribution in the
tumor and makes the drugs more effective.