MINIMALLY INVASIVE CRYOSURGERY - TECHNOLOGICAL ADVANCES

The technological advances which have caused renewed interest in cryos urgery are the development of intraoperative ultrasound to monitor the therapeutic process and the development of new cryosurgical equipment designed to use supercooled liquid nitrogen. The thin, highly efficie nt probes, available in several sizes, can be placed in diseased sites via endoscopy or percutaneously in minimally invasive procedures. The manner of use is to place the probe in the desired location in the di seased tissue with ultrasound guidance. If required by the size or loc ation of the tumor, as many as five probes can be inserted and cooled to -195 degrees C simultaneously. The process of freezing is monitored by ultrasound which displays a hypoechoic (dark) image when the tissu e if frozen. Rapid freezing, slow thawing, and repetition of the freez e/thaw cycle are standard features of technique. Clinical applications which have become common in the past 4 years include the treatment of prostatic cancer and liver tumors. The cases selected for cryosurgery are generally those for which no conventional treatment is possible. However, especially in prostatic cancer, the operative morbidity is so low and the results of therapy are sufficiently good in the short ter m to merit consideration of use in earlier stages of the disease. Dive rse tumors in other sites, such as the brain, bronchus, bone, pancreas , kidney, and uterus, have also been treated in small numbers by cryos urgery. Judging from this experience, further expansion in the use of cryosurgical techniques seems certain. (C) 1997 Academic Press.