Hyperthermic treatment of cutaneous malignancies.

Malignant cells are susceptible to high temperatures, and recent technical advances have allowed heat to be concentrated at the site of the neoplasm in vivo. The mechanism(s) of hyperthermic cytotoxicity is(are) unclear but may involve cellular accumulation of nuclear proteins, plasma membrane damage, and/or lysosomal effects. Three methods of localized hyperthermia delivery have been described: ultrasound, radiofrequency, and microwave. All involve production of high-energy save forms which are produced by passing electrical energy through an oscillator that produces heat of sufficient magnitude to cause tumor necrosis. Temperatures of at least 42 degrees C are necessary, but other factors, such as tissue pH, metabolic depletion, tissue hypoxia, and tumor vascularity, also influence cell killing. Hyperthermic treatment of cutaneous neoplasms may have great potential usefulness. Animal studies show high cure rates for squamous cell carcinoma with the use of radiofrequency hyperthermia. Human trials are needed before this technic can be considered suitable for clinical use.