Randomized Trial of Hyperthermia and Radiation for Superficial Tumors

Purpose
Randomized clinical trials have demonstrated hyperthermia (HT) enhances radiation response. These trials, however, generally lacked rigorous thermal dose prescription and administration. We report the final results of a prospective randomized trial of superficial tumors (! 3 cm depth) comparing radiotherapy versus HT combined with radiotherapy, using the parameter describing the number of cumulative equivalent minutes at 43°C exceeded by 90% of monitored points within the tumor (CEM 43°C T90) as a measure of thermal dose.

Methods
This trial was designed to test whether a thermal dose of more than 10 CEM 43°C T90 results in improved complete response and duration of local control compared with a thermal dose of ! 1 CEM 43°C T90. Patients received a test dose of HT ! 1 CEM 43°C T90 and tumors deemed heatable were randomly assigned to additional HT versus no additional HT. HT was given using microwave spiral strip applicators operating at 433 MHz.

Results
One hundred twenty-two patients were enrolled; 109 (89%) were deemed heatable and were randomly assigned. The complete response rate was 66.1% in the HT arm and 42.3% in the no-HT arm. The odds ratio for complete response was 2.7 (95% CI, 1.2 to 5.8; P ! .02). Previously irradiated patients had the greatest incremental gain in complete response:23.5% in the no-HT arm versus 68.2% in the HT arm. No overall survival benefit was seen.

Conclusion
Adjuvant hyperthermia with a thermal dose more than 10 CEM 43°C T90 confers a significant local control benefit in patients with superficial tumors receiving radiation therapy.