Surgical operations for cancer have been reported to induce dissemination of cancer cells into surrounding tissues or into the circulation10,11and infiltration anesthetics can inhibit immune response12-14. Although the mechanism remains to be elucidated, infiltration anesthetics such as lidocaine have membrane- stabilizing action (Seeman, 1972) and these agents could have direct effects on cancer cells. Therefore, it is important to clarify the effects of infiltration anesthetics on behavior of the tumor cells.