Thermotherapy is a technology aiming at destroying tissue, for example tumor tissue. Immunostimulating Interstitial Laser Thermotherapy (imILT) is a specific form of thermotherapy, which, in addition to destroying tumor tissue, has been optimized to cause a tumor specific immunologic response. In laboratory animals the imILT method has also been shown to induce a so called abscopal effect. This means that when one tumor is treated with imILT other, untreated, tumors also decrease in size.