Nakamura et al. retrospectively reviewed 20 patients with 89 pulmonary metastases from sarcomas. The median followup was 18 months, in which the median survival was 12.9 months and the 3-year survival rate was 29%. The only prognostic indicator on univariate Verdinexor (KPT-335)? and multivariate analyses in this study was the ability to ablate all lung tumors. Patients with complete ablation of all tumors had a 1- and 3-year survival rate of 88.9% and 59.2%, respectively. Pneumothorax again was the most common complication, which occurred in 38% of patients. Thus, the authors concluded that RFA for pulmonary metastases was a safe and beneficial therapeutic option for appropriate candidates . 3.2. Cryoablation Whereas RFA applies heat to treat the targeted tissue, cryoablation exposes tumors to freezing temperatures to treat various malignancies.
Cryoablation involves the insertion of dual chamber probe(s) into the target tissue. Typically, high pressure argon gas, which is supplied by a large in-room tank, is passed through the probe. Within a few seconds, there is rapid expansion and cooling, which leads to the production of temperatures of approximately ?100��C. This generates a ball of ice up to 3.5cm in size (Figures 3(a)-3(b)). Cell death is known to occur when temperatures are below ?20��C. Multiple probes can be used to allow for the creation of larger balls of ice and, thus, the treatment of larger lesions . Figure 3 Recurrent hepatocellular carcinoma after right lobe resection (a) and ablation zone (b). Cell death from cryoablation is due to ice formation within the cell through immediate freezing of tissue adjacent to the probe.
Gradual cooling away from the probe causes osmotic variation between the cell and membrane, leading to cell dehydration and eventual death . Cryoablation has been utilized in the treatment of liver metastasis, particularly from colorectal primaries. Weaver et al. reviewed 136 patients with unresectable liver metastases from colorectal primaries who underwent 158 cryoablation procedures for tumor control. The median preoperative carcinoembryonic antigen (CEA) level was 14.4ng/dL. Median survival was 30 months. Recurrent liver disease developed in 78% of patients, with 82% of these recurrences in the liver. Complication rates were comparable to liver resection and operative mortality was 3.7%.
This led the authors to conclude that hepatic cryoablation is effective and safe in treating colorectal hepatic metastases under image guidance . Cryoablation has also been used to palliate primary and metastatic bone lesions. AV-951 Callstrom and colleagues prospectively assessed pain outcomes in 14 patients with osseous metastases from various tumors treated with cryoablation. Posttreatment scores for pain relief, worst pain, pain interference with daily activities, and narcotic medication use decreased with the use of cryoablation .