Authors: Myerson RJ, Scott CB, Emami B, Sapozink MD, Samulski TV.
Publication: Int J Hyperthermia. 1996 Jul-Aug;12(4):449-59.
The purpose of this paper is to evaluate the safety and efficacy of deep hyperthermia in conjunction with radiation therapy.
METHODS and MATERIALS:
This study employed 'second generation' electromagnetic devices which were felt to be better able to confine heating and spare normal tissue than the devices evaluated in a previous study (RTOG 84-01). Sixty six patients at six institutions were enrolled on a prospective Phase I/II study. Eligible deep seated tumours were treated with a combination of external hyperthermia and radiation therapy. Radiation consisted of 1.7-2 Gy per fraction, 4-5 fractions per week, to > 20 Gy (previously irradiated lesions) or > 50 Gy (no previous radiation). Deep hyperthermia was delivered with electromagnetic devices: BSD 2000 for 92% of cases, Thermotron for 5% of cases, other low frequency electromagnetic for 4% of cases. Hyperthermia was delivered < or = twice weekly.
Overall complete and partial response rates were 34% and 16% respectively. Response was not correlated with maximum tumour temperature or disease site. There was, however, a strong association with radiation dose: 54% CR with > or = 45 Gy versus 7% with < 45 Gy (p < 0.0001). The achieved temperatures were less than ideal. Although the average maximum tumor temperature was 41.9 degrees C (range 35.7 degrees C-46.7 degrees C), the minimum tumour temperatures were low. The average minimum tumour temperature was 38.5 degrees C and was never > 41.8 degrees C. Treatment was well tolerated with no fatalities. There were four acute grade 3 or 4 toxicities (6% of patients). Patient discomfort resulted in interruption or discontinuation of sessions in 30% of the sessions. In 12 cases (18% of patients) the planned course of hyperthermia was discontinued due to acute discomfort.
The devices used in this study were better tolerated than the devices used in the previous Phase I/II deep hyperthermia trial (RTOG 84-01) with less patient discomfort and no problems with severe systemic cardiovascular stress. In the previous study 68% of the hyperthermia courses were prematurely terminated primarily due to patient discomfort and toxicity; in the present study 18% were prematurely terminated. However, as indicated by the low minimum tumour temperature, fundamental problems with achieving acceptable temperature distributions remain.