MECHANISMS OF TISSUE-INJURY IN CRYOSURGERY

As the modern era of cryosurgery began in the mid 1960s, the basic fea tures of cryosurgical technique were established as rapid freezing, sl ow thawing, and repetition of the freeze-thaw cycle. Since then, new a pplications of cryosurgery have caused numerous investigations on the mechanism of injury in cryosurgery with the intent to better define ap propriate or optimal temperature-time dosimetry of the freeze-thaw cyc les. A diversity of opinion has become evident on some aspects of tech nique, but the basic tenets of cryosurgery remain unchanged. All the p arts of the freeze-thaw cycle can cause tissue injury. The cooling rat e should be as fast as possible, but it is not as critical as other fa ctors. The coldest tissue temperature is the prime factor in cell deat h and this should be -50 degrees C in neoplastic tissue. The optimal d uration of freezing is not known, but prolonged freezing increases tis sue destruction. The thawing rate is a prime destructive factor and it should be as slow as possible. Repetition of the freeze-thaw cycle is well known to be an important factor in effective therapy. A prime ne ed in cryosurgical research is related to the periphery of the cryosur gical lesion where some cells die and others live. Adjunctive therapy should influence the fate of cells in this region and increase the eff icacy of cryosurgical techniques, (C) 1998 Academic Press.