Hyperthermia in eccentrically located pelvic tumors: excessive heating of the perineal fat and normal tissue temperatures.

Abstract

Regional hyperthermia in deep-seated tumors can be limited by excessive heating of normal tissues, usually associated with pain or local discomfort. In this report, 57 hyperthermia treatments in 8 patients with locally advanced presacral recurrences of colorectal cancer were analyzed with respect to normal tissue temperatures, especially with respect to the perineal fat temperature. In 27 treatments, 1 to 2 catheters had been inserted from the perineal region through a large part of the perirectal and presacral fat into the tumor, so that temperature profiles of the perineal fat could be obtained. The mean maximum temperature (+/- SD) of the vagina, rectum, bladder, muscle tissue, and perineal fat was 40.8 +/- 1.2 degrees C, 40.9 +/- 1.6 degrees C, 40.5 +/- 1.6 degrees C, 39.8 +/- 0.7 degrees C, and 42.6 +/- 1.1 degrees C, respectively. The mean maximum systemic temperature (+/- SD) was 37.7 +/- 0.7 degrees C. In 42% of the treatments, the temperature in the perineal fat ranged between 43 and 46 degrees C and was treatment-limiting. In conclusion, overheating of the perineal fat is a problem in the treatment of eccentrically located tumors of the presacral region when relatively high temperatures in the tumor will be maintained for longer time periods.