Background: Water-filtered infrared-A-radiation (IR/A-HT) can be used to heat superficial malignant tumors. A prospective multicenter phase I-II study was conducted to evaluate toxicity and efficacy of IR/A-HT combined with external beam radiotherapy (RT).
Patients, material and methods: From December 1991 to June 1994, a total of 53 patients with 58 malignant lesions were entered in the study. There were 14 primary, 36 recurrent and 8 metastatic tumors which were located in the head and neck region (14), chest wall (31), abdominal wall (2) and the extremities (11). The mean tumor volume was 100 cm3. IR/A-HT was applied 1 to 2 times per week with up to 3 IR/A-HT-radiators directly before or after external RT for 1 hour at 40.5 to 44 degrees C. Temperatures were controlled at various locations at the skin surface and invasively at depth.
Results: IR/A-HT was well tolerated: in 31 (53%) lesions acute (pain, pulse or blood pressure changes, increased skin reaction etc.) and in 25 (43%) chronic side-effects (atrophy, telangiectasis, fibrosis etc.) were noted; usually the toxicity was minor and temporary. At 3 months FU, 32 (55%) lesions achieved a local CR and 19 (35%) a PR; at 12 months FU, 25 (43%) had persistent CR; 16 patients (18 lesions) were deceased and 3 (4 lesions) not yet in FU. In univariate analysis the following prognostic factors for CR at 3 or 12 months FU were found: Karnofsky, metastatic status, tumor size, total RT-dose, thermal parameters T min(av) and T mean. For acute toxicity maximum temperature Tmax(av) was prognostically decisive. Significant differences were also found when considering the "quality of the HT-application". The microwave technique was superior to the infrared-A-HT-technique with regard to the penetration depth of energy deposition.
Conclusions: Water-filtered infrared-A-radiation can be safely and effectively applied to heat localized superficial tumors (up to 1 cm depth). To increase the area of HT application multiple infrared-A-radiators have to be combined. A multi-element-system is in progress.