An electrosurgical device for performing invasive electrosurgery, the electrosurgical device comprising: a handpiece; an instrument cable connected to and extending away from the handpiece, the instrument cable comprising a coaxial layered energy conveying structure having: an inner conductive layer; an outer conductive layer formed coaxially with the inner conductive layer; a dielectric layer separating the inner conductive layer and the outer conductive layer, wherein the inner conductive layer, the outer conductive layer and the dielectric layer form a coaxial transmission line for conveying radiofrequency and/or microwave electromagnetic energy, wherein the inner conductive layer is hollow to form a longitudinal passage, and wherein the energy conveying structure further comprises an optical channel for conveying optical radiation, the optical channel being located in the longitudinal passage; and an instrument tip mounted at a distal end of the instrument cable, wherein the instrument tip is connected to the coaxial transmission line to deliver the radiofrequency and/or microwave EM energy received from the energy conveying structure, characterized in that the handpiece comprises a steering mechanism for controlling an orientation of a distal portion of the instrument cable, wherein the steering mechanism comprises: an actuator mounted on an outer surface of the handpiece; a pull arm operably coupled to the actuator to slide within the handpiece and a control element extending along the instrument cable, the control element being operably coupled to the pull arm and the distal portion of the instrument cable, and wherein the control element comprises a protective sheath that surrounds the coaxial layered structure, wherein the protective sheath is anchored to the coaxial layered structure at the distal portion of the instrument cable and free to move relative to the coaxial layered structure at the handpiece, and wherein the coaxial layered structure is anchored to the handpiece. a handpiece; an instrument cable connected to and extending away from the handpiece, the instrument cable comprising a coaxial layered energy conveying structure having: an inner conductive layer; an outer conductive layer formed coaxially with the inner conductive layer; a dielectric layer separating the inner conductive layer and the outer conductive layer, wherein the inner conductive layer, the outer conductive layer and the dielectric layer form a coaxial transmission line for conveying radiofrequency and/or microwave electromagnetic energy, wherein the inner conductive layer is hollow to form a longitudinal passage, and wherein the energy conveying structure further comprises an optical channel for conveying optical radiation, the optical channel being located in the longitudinal passage; and an inner conductive layer; an outer conductive layer formed coaxially with the inner conductive layer; a dielectric layer separating the inner conductive layer and the outer conductive layer, wherein the inner conductive layer, the outer conductive layer and the dielectric layer form a coaxial transmission line for conveying radiofrequency and/or microwave electromagnetic energy, wherein the inner conductive layer is hollow to form a longitudinal passage, and wherein the energy conveying structure further comprises an optical channel for conveying optical radiation, the optical channel being located in the longitudinal passage; and an instrument tip mounted at a distal end of the instrument cable, wherein the instrument tip is connected to the coaxial transmission line to deliver the radiofrequency and/or microwave EM energy received from the energy conveying structure, characterized in that the handpiece comprises a steering mechanism for controlling an orientation of a distal portion of the instrument cable, wherein the steering mechanism comprises: an actuator mounted on an outer surface of the handpiece; a pull arm operably coupled to the actuator to slide within the handpiece and a control element extending along the instrument cable, the control element being operably coupled to the pull arm and the distal portion of the instrument cable, and an actuator mounted on an outer surface of the handpiece; a pull arm operably coupled to the actuator to slide within the handpiece and a control element extending along the instrument cable, the control element being operably coupled to the pull arm and the distal portion of the instrument cable, and wherein the control element comprises a protective sheath that surrounds the coaxial layered structure, wherein the protective sheath is anchored to the coaxial layered structure at the distal portion of the instrument cable and free to move relative to the coaxial layered structure at the handpiece, and wherein the coaxial layered structure is anchored to the handpiece.