WHOLE-BODY HYPERTHERMIA COMBINED WITH HYPERFRACTIONATED IRRADIATION OF THE THORAX IN DOG - ACUTE PHYSIOLOGICAL-RESPONSE

Whole-body hyperthermia has potential as an adjuvant treatment with ch emotherapy and radiation therapy for diseases such as lung cancer whic h require both local and systemic control. The acute toxicity of whole -body hyperthermia combined with whole-thorax irradiation was studied in dogs. Twenty-eight dogs received three 2-h whole-body hyperthermia (WBH) treatments at 42.0-degrees-C deep rectal temperature. Twenty-fou r of these dogs were also randomized to receive radiation doses of 18, 22.5, 27, 31.5, 40.5 or 45 Gy. Irradiation was given in 1.5 Gy fracti ons over 6 weeks. Three WBH treatmens were given to 28 dogs with all d ogs surviving treatment. WBH was given on days 1, 22 and 40 of the 6-w eek interval. Thirty-one dogs received radiation doses of 18-49.5 Gy w ithout WBH. Deep rectal temperature was maintained at 41.9 +/- 0.3-deg rees-C over 2 h with an average of 20 min outside the chamber for irra diation. Two dogs required intervention with emergency medications dur ing WBH treatment. One of the two dogs developed permanent neurologica l injury. Continuous physiological monitoring was necessary for succes sful WBH. WBH plus thoracic irradiation was well tolerated. All dogs s urvived all treatments. A significant but transient increase in periph eral blood leucocytes and a decrease in platelet counts occurred after each WBH treatment. The addition of thoracic irradiation up to 45 Gy in 1.5 Gy fractions did not appear to alter the acute toxicity of WBH with the exception of an increase in the protein content of lung lavag e fluids. In conclusion, multiple WBH treatments of 2 h at a target te mperature of 42-degrees-C in addition to thoracic irradiation up to 45 Gy in 1.5 Gy fractions was administered with only mild acute toxiciti es occurring. Core temperature could be maintained for up to 20 min ou tside of the WBH chamber which allowed irradiation to be given concurr ently with hypertherm ia at a core temperature of 42-degrees-C +/- 0.1 -degrees-C.