Hyperthermia (HT) can act as a radiosensitizer by
- increasing tumour perfusion and oxygenation
- inhibitiing DNA repair
- increasing immunological effects.
While different temperatures are optimal for these mechanisms, the whole temperature range of 39-43°C has been described as effective in combined hyperthermia/radiotherapy (HT/RT).
In order to achieve the most beneficial effects, the time gap between hyperthermia and radiotherapy treatment should be as short as possible.
The combination with HT enables effective tumour control with
- significantly reduced RT dosage and toxicity
- option of safe re-irradiation even in cases where re-irradiation in therapeutic dosage alone is not an option or associated with the risk of severe side-effects.
Randomized clinical studies comparing the combined HT/RT against RT alone showed an especially high benefit for pre-irradiated patients.
Good thermometry is crucial for quality assurance of HT treatments. Superficial temperatures can be measured by contact sensors and (in case of hydrosun®-TWH1500) by thermography. Invasive thermometry by intra-tumoral temperature sensors is restricted to punctual measurements, and the high heterogenity of tumours has to be taken into account.
Some of the described synergistic effects of HT can also work in combination with chemotherapy.