Using units of CEM 43 degrees C T-90, local hyperthermia thermal dose can be delivered as prescribed

A randomized study was designed in dogs with spontaneous soft tissue sarcom as to gain information about the relationship between hyperthermia dose and outcome. The study compared two levels of thermal dose applied to dogs wit h heatable tumours, so it was necessary to deliver either a low (2-5 CEM 43 degrees C T-90) or high (20-50 CEM 43 degrees C T-90) thermal dose as prec isely as possible. It was also desirable to have similar numbers of hyperth ermia treatments in each thermal dose group. Identification of heatable tum ours and randomization to high or low heat dose group was done during the f irst hyperthermia treatment. This was readily accomplished using mapping of temperatures in thermometry catheters, manual recording of thermal data, a nd visual inspection of raw thermal data with subsequent adjustment of the duration of the hyperthermia treatment. An analysis of precision of thermal dose delivery was conducted after approximately 50% of projected accrual h ad been met in a randomized phase III assessment of thermal dose effect. Fi fty-four dogs were eligible for randomization; in 48 dogs the tumour was de emed heatable according to predetermined temperature criteria applied durin g the first heat treatment. Twenty-four dogs were randomized to the high he at dose group, and 24 to the low heat dose group. Median (range) total ther mal dose for dogs in the high dose group was 43.5 CEM 43 degrees C T-90 (16 .4-66.6) compared to 3.2 CEM 43 degrees C T-90 (2.1-4.6) for dogs in the lo w dose group. There was no overlap of thermal doses between groups. Thus, t hermal dose could be delivered accurately, being within the predetermined r ange in 47 of the 48 dogs. Thermal dose quantified as CEM 43 degrees C T50, however, did overlap between groups and the clinical significance of this finding will not be known until outcome data are analysed. Most dogs in bot h groups received five hyperthermia treatments. Median (range) treatment du ration for dogs in the high dose group was 300 min (147-692) compared to 11 1 min (51-381) for dogs in the low dose group. Relatively simple but accura te methods of delivering prescribed thermal dose as described herein will a id the translation of clinical hyperthermia from the research setting into more general practice once the characteristics of the relationship between hyperthermia dose and outcome are understood.