One potential candidate for a new approach to advanced lung cancer therapy is hyperthermia because lung cancer cells are thermo-sensitive, with significantly reduced heat shock protein (HSP) expression. Moreover, hyperthermia (42°C) causes repression of genes involved in the cell cycle and cellular growth and proliferation. Upon exposure to hyperthermic conditions, HSP expression is increased in normal cells. However, when cancer cells are exposed to hyperthermia, they initially express significantly less HSPs than normal cells, which sensitizes them to hyperthermia. Mild hyperthermia (43°C for less than two hours) induces extensive double-stranded DNA fragmentation and, at a later time, apoptosis in murine thymocytes. In cells with irreparable levels of DNA damage, apoptosis is the means of elimination.