Objective: The aim of the present study is to evaluate the correlation between the thermal parameters of hyperthermia and the clinical outcome in patients with superficial tumours.
Methods: In this study, 20 patients were included with either submandibular lymph nodes from head and neck cancer, or breast cancer relapses post-mastectomy. They were treated with radiation in combination with one session of 433 MHz microwave hyperthermia (1 hour, 42.5 °C-46 °C). The dose of irradiation ranged from 54 to 60 Gy. The thermal parameters calculated were the minimum volume temperature, the maximum volume temperature and the time interval where the volume temperature was greater than 44 °C.
Results: All patients responded positively to the combined treatment and 60% of the patients showed a complete response. Of the three parameters tested, the only parameter that was found to correlate with the reduction of the tumour diameter was the time with volume temperatures greater than 44 °C (p < 0.001, Spearman rho). No moderate toxicity was observed.
Conclusion: Microwave heating should be over 44 °C for favourable treatment response, when combined with radiotherapy. More patients are needed to confirm the above results.