The present invention relates to a method of removing a tumor by radiofrequency ablation, comprising providing a guiding device (6) having at least two first concentric through holes (8, 81, 82) and a plurality of second through holes (10, 11) at a periphery of the guiding device (6). The method further comprising placing the guiding device against the skin of a patient and inserting two first electrodes (3, 4, 5) into the first through holes (8, 81, 82) of the guiding device and into a patient's skin and then applying a first radiofrequency current between the two first electrodes (3, 4, 5). The method further comprising inserting a second electrode (5) through a second through hole (10, 11) and into the patient's skin and then applying a second radiofrequency current between a first electrode (3, 4) and the second electrode (5).
