IMAGE-GUIDED
CRYOABLATION
METASTASIS LIVER CANCER
STATISTICS
The liver ranks second only to the lymph nodes as a common site of metastasis of cancers from other organs. Specifically, the liver is a common site of metastasis from gastrointestinal tumors. It is commonly believed that this is because of dissemination via the portal vein system. In the United States, the most common extrahepatic primary cancer associated with secondary liver cancer is colorectal cancer, and metastasis to the liver is the leading cause of death in patients with colorectal cancer. Approximately 20% of the nearly 160,000 Americans diagnosed with colorectal cancer each year will have liver metastases at presentation. An additional 20-30% will develop liver metastases subsequent to treatment of their primary cancer. This means that every year there are approximately 64,000 – 80,000 cases of liver tumors metastatic from colorectal cancers alone. In only 30% of these cases the metastatic disease is confined to the liver.
Studies published peer-reviewed medical literature suggests only 10-25% of patients with liver metastases from any primary site meet the criteria for surgical resection. The remaining 75-90% of patients are not appropriate candidates due to the existence of bilobar or extrahepatic disease, unfavorable tumor biology, more than four metastatic tumors, or the inability to achieve an adequate tumor-negative surgical margin because of the tumor’s proximity to major vascular or biliary structures.
Systemic chemotherapy has been widely employed for unresectable disease and is associated with only a 20-40% response rate with little impact on long-term survival. As a result, physicians continue to evaluate local and targeted systemic therapies. Percutaneous ethanol injection, hepatic artery embolization, cryoablation and radiofrequency ablation (RFA) are among the alternative local treatment options currently available. Among these techniques, it is believed that only cryotherapy and RFA have been shown to have curative potential, while transarterial chemoembolazation and ethanol injection are considered palliative options only.
Many of the studies in published peer-reviewed medical literature have evaluated the efficacy of cryoablation of liver tumors but have not compared it to the gold standard of surgical resection. Cryoablation is among the standard treatment options recommended by the National Cancer Institute for selected patients with unresectable liver metastases. The results of the available clinical studies suggest that cryoablation of unresectable metastatic liver cancer is a relatively safe, acceptable procedure for short term control of single or multiple small tumors. Until longer term results of randomized clinical trials are available, most investigators caution against the use of cryotherapy to treat resectable disease. |
