Histopathological observations in the canine prostate treated by local microwave hyperthermia

A large series of repeated experiments were performed applying localized microwave hyperthermia to the prostate in dogs using a new water‐cooled skirt‐type antenna [1], operating at 915 MHz, as part of a new hyperthermia apparatus being developed for the treatment of the prostate in humans. The prostate gland of 20 male dogs was heated repeatedly under general anesthesia, at temperatures between 40°C and 47°C, and for different lengths of time up to 10 h. The prostate and other tissues were evaluated histopathologically following treatments. Invariably, all treatments by hyperthermia of the prostate caused a mononuclear inflammatory infiltration in the interstitium and polymorphonuclear inflitration in the glandular elements. Permanent tissue damage was found to be time‐and temperature‐dependent. Heating at 42.5°C (± 0.5°5C) for up to 1.5 h was found to be harmless and could be safely repeated with our equipment. This study was part of a preclinical evaluation of a new antenna and apparatus.