An electrosurgical resection instrument (200, 282, 402) for applying to radiological tissue (206) radiofrequency (RF) electromagnetic energy (EM) having a first frequency and microwave EM energy having a second frequency greater than the first frequency , the instrument comprising: an instrument tip (202, 283, 300) comprising a body made of a first dielectric material (416) that separates a first conductive element (284) from a second conductive element (286)； a coaxial power cable (224, 406) comprising an internal conductor (418), an external conductor (420) coaxial to the internal conductor, and a second dielectric material that separates the external and internal conductors, the coaxial power cable being transport, simultaneously or separately, an RF signal having the first frequency and a microwave signal having the second frequency； and a fluid supply conduit (408) for supplying fluid to the tip of the instrument； wherein the internal conductor is electrically connected to the first conductor element and the external conductor is electrically connected to the second conductor element to allow the tip of the instrument to receive the RF signal and the microwave signal, and in which the first and the Second conductive elements are arranged to act: as active and return electrodes for transporting RF EM radiation corresponding to the RF signal, and as an antenna for emitting microwave EM radiation corresponding to the microwave signal, characterized in that: the conduit Fluid feeding is arranged to supply liquid to the tip of the instrument, the fluid feeding conduit having an outlet (296) at the distal end of the tip of the instrument to introduce the liquid into the biological tissue.Un instrumento de resección electroquirúrgico (200, 282, 402) para aplicar a tejido biológico (206) energía electromagnética (EM) de radiofrecuencia (RF) que tiene una primera frecuencia y energía EM de microondas que tiene una segunda frecuencia mayor que la primera frecuencia, comp
