An apparatus and method for thermally destroying tumors. A tip has a plurality of deployable thermal conductive elements whose temperatures are individually controllable. This allows the shape of the thermal field to be controlled and for specific areas to be protected from excessive heat by cooling those specific areas while ablating other areas. In another embodiment, the deployable thermal conductive elements are individually deployable to various lengths to further aid in shaping the thermal field. The temperatures and the shape of the thermal field may be monitored and controlled by a data processing device, such as a microprocessor. Further selectivity in defining the area of tissue to be treated may be achieved by introducing into the tissue thermal additives that alter the thermal properties of the tissue.
