The effect of high-energy shock wave therapy combined with cisplatin on mouse hepatoma.

It is well documented that high-energy shock waves (HESW) can produce antitumor effects in vivo and in vitro. Furthermore, because HESW can be focused on a limited area, this therapy is considered applicable to the treatment of localized cancer. In this study, we investigated the effects of HESW therapy combined with cisplatin (CDDP) on MH134 hepatoma in a mouse model. Tumor growth was inhibited by 1 mg/kg CDDP treatment in combination with 2,000 HESW administration, but not by 1 mg/kg CDDP treatment only. Moreover, the CDDP concentration in the tumor increased after HESW administration. The active oxygen induced by HESW was then investigated by the electron spin resonance system, and it was found that HESW generated hydroxy-radicals. As oxygen radicals have been reported to change cell membrane potential, it is supposed that active oxygen induced by HESW changes cell membrane permeability, and that CDDP is concentrated in the tumor. Therefore, the combined therapy with HESW and CDDP showed synergistic inhibitory effects on tumor growth.