An apparatus for obtaining an anti-tumour immunologic response by thermotherapy of a treatment lesion covering at least a portion of a tumour is disclosed. The apparatus comprises a heating probe comprising an optical fiber and a cooling catheter. The optical fiber is inserted in the cooling catheter. Further the heating probe has a light emitting area, and the heating probe is interstitially insertable into the tumour of the treatment lesion. The heat probe is internally cooled by a fluid circulating in said catheter. The apparatus further comprises a first thermal sensor member having at least one sensor area. The first thermal sensor member is positionable at a distance from said boundary. The apparatus also comprises a control unit for controlling a power output of said light source based on a measured first temperature.
