An electrosurgical apparatus for delivering radiofrequency energy and microwave energy into lung tissue, the electrosurgical apparatus comprising: a generator for generating RF energy and microwave energy separately or simultaneously; an electromagnetic navigation bronchoscope having a steerable instrument cord for non-percutaneous insertion into a patient's lungs, the instrument cord having an instrument channel running along its length; an electrosurgical instrument comprising: a coaxial cable connected to the generator and arranged to convey RF energy and microwave energy, the coaxial cable having an inner conductor, an outer conductor, and a dielectric material separating the inner conductor and outer conductor; and a radiating tip portion disposed at a distal end of the coaxial cable to receive the RF energy and microwave energy from the coaxial cable, wherein the radiating tip portion comprises a first conductive element electrically connected to the inner conductor and a second conductive element electrically isolated from the inner conductor, wherein the first conductive element and the second conductive element form a plurality of radiating slots (222, 224, 226) formed by removing the outer conductor from a plurality of circumferential regions of the coaxial cable to expose the dielectric material, and wherein the first conductive element and the second conductive element are arranged to act as: an active electrode and a return electrode for delivering the RF energy into tissue surrounding the radiating tip portion, and an antenna for radiating the microwave energy as a localized microwave field, and wherein the electrosurgical instrument is insertable through the instrument channel of the steerable instrument cord in the electromagnetic navigation bronchoscope. a generator for generating RF energy and microwave energy separately or simultaneously; an electromagnetic navigation bronchoscope having a steerable instrument cord for non-percutaneous insertion into a patient's lungs, the instrument cord having an instrument channel running along its length; an electrosurgical instrument comprising: a coaxial cable connected to the generator and arranged to convey RF energy and microwave energy, the coaxial cable having an inner conductor, an outer conductor, and a dielectric material separating the inner conductor and outer conductor; and a radiating tip portion disposed at a distal end of the coaxial cable to receive the RF energy and microwave energy from the coaxial cable, a coaxial cable connected to the generator and arranged to convey RF energy and microwave energy, the coaxial cable having an inner conductor, an outer conductor, and a dielectric material separating the inner conductor and outer conductor; and a radiating tip portion disposed at a distal end of the coaxial cable to receive the RF energy and microwave energy from the coaxial cable, wherein the radiating tip portion comprises a first conductive element electrically connected to the inner conductor and a second conductive element electrically isolated from the inner conductor, wherein the first conductive element and the second conductive element form a plurality of radiating slots (222, 224, 226) formed by removing the outer conductor from a plurality of circumferential regions of the coaxial cable to expose the dielectric material, and wherein the first conductive element and the second conductive element are arranged to act as: an active electrode and a return electrode for delivering the RF energy into tissue surrounding the radiating tip portion, and an antenna for radiating the microwave energy as a localized microwave field, and an active electrode and a return electrode for delivering the RF energy into tissue surrounding the radiating tip portion, and an antenna for radiating the microwave energy as a localized microwave field, and wherein the electrosurgical instrument is insertable through the instrument channel of the steerable instrument cord in the electromagnetic navigation bronchoscope.