Increasing the systemic temperature during regional hyperthermia: effect of a cooling strategy on tumour temperatures and side-effects

Abstract

In the application of regional hyperthermia, optimization of the temperature distribution remains necessary. One of the tools that might be used is a modest increase in the systemic temperature to diminish cooling by blood perfusion. This study investigates (1) if it is feasible to increase the systemic temperature by applying other cooling strategies, without inducing unacceptable systemic stress, and (2) whether a rise in systemic temperature results in improvement of tumour temperatures. Eleven patients with locally advanced cervical carcinoma and 12 patients with locally advanced prostate carcinoma were treated with our Coaxial TEM regional hyperthermia system. In this system, the temperature of the open water bolus can be easily adjusted. Two cooling methods were applied alternately, one with a relatively low water temperature (method A), the other with a higher water bolus temperature in combination with extensive head/chest cooling by a hand shower (method B). Method B resulted in significantly higher systemic temperatures, for both patient groups separately (0.8, respectively, 0.5°C) and for the total patient group (0.7°C). Additionally, all tumour index temperatures were higher. For the combined group (for T50: 0.4°C) and for the cervix group (for T50: 0.7°C), it reached statistical significance. The raise in core temperature led to a significantly higher increase in heart rate. For the group of cervix patients, higher systemic temperatures resulted in more treatment-limiting systemic stress. For the prostate patients, systemic stress was not an important issue. Since the raise in systemic temperature did not influence the overall tolerance of treatment, method B could be applied to this group. However, the increases in tumour temperatures were small, and potential hazards of systemic temperature increase should be considered.