Cryosurgical Control of Cancer: Effects of Freeze Rates, Tumor Temperatures, and Ischemia

Abstract

These studies in mice show that, in order to control malignant tumors consistently by cryosurgery, it is important to utilize low probe-tip temperatures, large probe lip-to-tumor contact surfaces or liquid nitrogen sprays, repetitive probe applications, spontaneous thaw between freezes, freezing to tumor temperatures below −30° C, and rapid rates of freezing. In the experimental tumor-host system, ischemia induced either by local administration of pharmacologic doses of epinephrine or by temporary clamping significantly potentiated heat extraction as reflected in tumor control and the time course of recurrences. The effects of ischemia are seen primarily in the thaw portion of the freeze-thaw cycle, during which time spontaneous thawing is consistently prolonged.