A method of selectively killing cancer cells uses a low-temperature plasma jet device. When cancer cells are simultaneously treated with ATR and PARP-1 inhibitors, followed by synchronization of a circadian rhythm and treatment with low-temperature atmospheric-pressure plasma, cancer cell death may be maximized about ten-fold or more compared to when treated with existing low-temperature atmospheric-pressure plasma alone, and thus this method may be usefully used as a future tumor treatment method.
