Thermal enhancement of radiation response: a growth delay study on superficial human tumour metastases

In a quantitative study of 96 nodules in 10 patients, an enhancement of radiation response has been demonstrated following the addition of a single heat treatment 3-4 h after a single dose of radiation. Thermal enhancement ratios ranging from greater than 1.6 to 4.2 have been derived from growth-delay curves obtained by ultrasonic and caliper tumour volume measurements. Nodules subjected to heat and radiation regress more rapidly than those receiving radiation alone, with median tumour volume halving times of 15.5 and 70 days, respectively. The total volume reduction was greater in heated nodules and the nadir values were observed later compared with nodules receiving radiation alone.