An apparatus for producing an immune response by thermal treatment of a tumor is disclosed. The apparatus has a lead configured to be arranged within and/or near boundaries of the tumor to be heat treated. The lead includes a heat source. The apparatus also has a thermal sensor positionable adjacent to the heat source for measuring a first temperature in the tumor adjacent the thermal sensor. Further, the apparatus has a control unit for adjusting a power output of the heat source based on the measured first temperature. The control unit is further configured for controlling a second temperature of tissue to be heated in a range of 42.5°C to 48°C.
