Tuesday, June 9, 2015
By: Dr. Lee Hammontree, Urology Centers of Alabama
Cryosurgery is the use of extreme cold produced by argon gas to destroy abnormal tissue. This technique is used to treat external growths on the skin. External growths can include benign and malignant skin conditions and warts. Gas is circulated through a hollow instrument called a cryoproge to target the growth filling the cells with crystals comprised of ice to destroy the cells by ripping them apart.
Cryosurgery can also be used on tumors inside the body. When using cryosurgery for internal tumors, an ultrasound or MRI is used to guide the cryoprobe and monitor the freezing process to minimize the damage done to healthy tissue. Often more than one probes will be used to deliver the gas to different parts of the tumor.
During these procedures, an ultrasound probe, which goes through a laparoscopic port is used for intra-operative real-time imaging of the mass and monitoring of the freezing process. It is usually an transabdominal laparoscopic approach and the size limit has been tumors 4cm in size or less. When the tumor is posterior, the procedure may be done in an extra peritoneal laparoscopic approach which leads to less intra-abdominal morbidity. A biopsy with a true cut spring loaded biopsy needle is performed immediately preceding placement of the cryoprobe so that there is pathological documentation of the mass. The cryoprobe is capable of production of an “ice ball” formation with temperatures reaching less than negative 40 degrees C. Depending on the size of the mass and its configuration, either multiple or single probe use may be needed. It is recognized that tumors 4cm or less in size constitute appropriate tumors to be considered for laparoscopic cryoablation of renal tumors. In some patients, it may be necessary to use a hand assisted laparoscopic approach or even an open approach for cryoablation procedures. There may be times that a CT guided percutaneous approach would be indicated.
Laparoscopic cryoablation for renal masses 4cm or less is an effective treatment for small renal masses. We are less likely to recommend this treatment in tumors approaching 4cm and would recommend robotic partial nephrectomy for those tumors. Complexity scoring of the tumor is useful and increased complexity correlates to complication rates. Cancer outcomes are excellent and the local recurrence rate is very low in tumors under 3.5cm.