Current Status of Clinical Hyperthermic Oncology in Japan

Clinical trials of hyperthermia in combination with radiation therapy or chemotherapy undertaken over the past decades in Japan are reviewed. Heating devices that had been originally developed and which were used mostly for these trials include RF (radiofrequency) capacitive heating devices, a microwave heating device with a lens applicator, an RF intracavitary heating device, an RF current interstitial heating device, and ferromagnetic implant heating device. Nonrandomized trials for locally advanced breast cancers, esophageal cancers, lung cancers, liver tumors, gastric cancers, colorectal cancers, and invasive urinary bladder cancers demonstrated a higher response rate in thermoradiotherapy than with radiotherapy alone. Randomized trials undertaken for esophageal cancers and gastric cancers also demonstrated improved local response with the combined use of hyperthermia. Furthermore, the complications associated with treatment were not generally serious except for chronic bowel damage suggested in a trial for colorectal cancers. These clinical results indicate the benefit of combined treatment of hyperthermia and radiotherapy for various malignancies. On the other hand, the presently available heating devices are not satisfactory from the clinical point of view. With advances in heating and thermometry technologies, hyperthermia will be more widely and safely used in the treatment of cancers.