An anti-cancer drug for use in a method for killing or inhibiting the growth of cancer cells in a target region, the method comprising the simultaneous steps of treating the cancer cells with the anti-cancer drug and applying an electric field to the target region for a period of time while the cancer cells are being treated with the anti-cancer drug, wherein the electric field is configured to damage the cancer cells or inhibit growth of the cancer cells but leaving normal cells in the target region substantially unharmed, wherein the electric field is an AC electric field having a frequency between 100 kHz and 300 kHz.