Apparatus modifications for experimental cryogenic surgery of cancer

Abstract A device has been described to conveniently position and hold several microthermocouples for measuring temperature changes in tissues subjected to cryogenic temperatures. Probe sleeves with different tip surface areas and configurations were fashioned to study variations in surface contact and heat transfer to tumor implants. Tumors were frozen until an iceball of standard size was achieved, extending visibly beyond gross tumor margins into normal adjacent tissues. The effects of varying probe-tip surface area and number of freezes were evaluated with respect to temperature changes in the frozen tissues and effectiveness of tumor control. Wide ranges of tissue temperature change resulted from varying these conditions, even though the visible iceball size was kept constant. Repeated freezing with either probe tip increased tumor cure rates. Relatively large tip-to-tumor contact area produced greater depth of subfreezing temperatures more promptly in the target area and led to superior tumor control as compared to the smaller probe.