Hyperthermia and the need to monitor temperature

Extensive biologic research has shown that adjuvant thermal therapy, i.e. heating tumors to 40-43°C, is a promising approach to increase the efficacy of existing radio- and chemotherapy protocols. The fact that in clinical trials, hyperthermia has shown not to increase toxicity is a major drive to invest in developing innovative devices and applicators to deliver thermal therapies. Moreover, the recent demonstrated ability of hyperthermia to decrease the repair of DNA double strand breaks provides a gateway to new treatments strategies involving hyperthermia and in combination with temperature sensitive drug carriers hyperthermia can be used for triggered local drug delivery. A point of concern, however, is that the quality of hyperthermia, i.e. the height of the achieved tumor temperature is closely related to its effectiveness, whereas in clinical practice application of hyperthermia is hampered by a low ability to control energy deposition and poor quality of temperature monitoring. In the light of our quest to control and prescribe hyperthermia quality the progress with regard to non-invasive thermometry and hyperthermia treatment planning should be considered to provide the gate-way to next generation of hyperthermia systems. Hybrid systems combining simultaneous heating and noninvasive thermometry are excellent to verify the temperature distribution. However, non-invasive thermometry cannot provide a prospectively evaluation of the potential quality of the hyperthermia treatment. For this purpose accurate hyperthermia treatment planning holds a pivotal position, as hyperthermia treatment planning is the only tool that has the potential to evaluate a priori the thermal dose to be delivered and to perform on-line optimization of the thermal dose.