Cryosurgery for hepatic tumor ablation

Cryosurgery is a method of in situ destruction of tumors using subfreezing temperatures (<-20 degrees to -30 degrees C). Intraoperative ultrasonography is utilized for accurate placement of cryoprobes and precise monitoring of the freeze front. This allows the application of cryosurgery to treatment of deep liver tumors, since the visible freeze front can be monitored in real time to ensure complete ablation of tumor sites with extension of the cryolesion beyond the tumor margins into the adjacent surrounding liver. The morbidity from the procedure is fairly low and primarily involves bleeding at the cryosurgical site from cracks in the liver capsule. Length of stay is on average 2 to 3 days less for cryosurgical ablation than for hepatic resection. Actuarial survival curves at 3 and 5 years show comparability to published surgical survival curves. It should be noted, however, that there is no evidence of plateau in the survival curve, even at 5 years; hence, further long-term follow-up studies are necessary. Surgical resection remains the definitive treatment for liver cancer, but most patients are technically unresectable. A certain percentage of these patients may benefit from cryosurgical ablation, which allows for sparing more liver parenchyma. The precise role of cryosurgical ablation relative to other therapeutic modalities, such as percutaneous ablative techniques, hepatic artery chemo embolization, and newer techniques such as gene therapy, will require much further study.