Improving superficial hyperthermia treatment: Temperature matters

In the Netherlands, annually approximately 15.000 women are diagnosed with invasive breast cancer. Within 10 years after surgery, 6.9% of the women develop a local and/or regional recurrence. Treatment options for locoregional recurrent breast cancer are limited, especially when the recurrence is located in previously irradiated area. After treatment with chemotherapy and, when possible, surgery, adjuvant re-irradiation and hyperthermia can be considered. Hyperthermia, heating the tumor for approximately one hour at 40-44°C, increases the effectiveness of irradiation. Goal of this research was to improve the hyperthermia treatment delivery of patients with locoregional recurrent breast cancer in previously irradiated area, to achieve a higher locoregional tumor control rate.
We found a hyperthermia dose-effect relationship in patients with locoregional recurrent breast cancer treated with re-irradiation and hyperthermia. Patients with irresectable locoregional recurrent breast cancer had a significant higher complete response rate when they received a high thermal dose versus a low thermal dose. Patients who received post-operative re-irradiation combined with high dose hyperthermia had significantly improved local control without additional toxicity compared to patients receiving low dose hyperthermia, three year local control was 92% vs. 74%, respectively. However, high dose hyperthermia can result in thermal toxicity, i.e. blisters. A thermal monitoring sheet with 56 sensors was developed and clinically tested to monitor the skin temperature more accurately during hyperthermia treatment. Clinical application of the thermal monitoring sheet will improve the quality of hyperthermia treatment because a higher tumor temperature can be achieved without inducing thermal toxicity, resulting in improved clinical outcome.