Ablation for liver cancer refers to the use of localized chemical or thermal means to destroy tumors that doctors can't remove surgically, according to the American Cancer Society. It works best when the tumors are confined to the liver and measure 2cm or less across. In general, ablation procedures result in cancer survival rates that are roughly equivalent to those seen in patients who have had surgery to remove liver tumors.
The Procedures
Radio-frequency ablation is the most frequently used ablation technique for liver tumors and in many cases doctors perform the procedure through the skin, explains Cancernews, a website that features referenced articles written by physicians who specialize in cancer research and treatment. Guided by computed tomography, ultrasound or magnetic resonance imaging, a doctor places an electrode into the liver tumor and then an electric current is sent into the body. By agitating water molecules near the electrode, the electric current heats the tissue to around 194 degrees Fahrenheit, and tumor cells die quickly once the temperature gets past 140 degrees.
According to Cancernews, ethanol injection through the skin is one of the image-guided tumor ablation techniques that doctors can use to treat liver cancer. This is a chemical method in which ethanol is injected directly into the liver tumor by means of a thin needle inserted through the skin of the abdomen. Ultrasound and computed tomography images guide the placement of the needle into the tumor, and the ethanol kills the tumor cells by dehydrating them.
Cryoablation is an image-guided thermal method of destroying liver cancer cells in which doctors use extremely cold temperatures, below minus 4 degrees Fahrenheit, to destroy the cancer cells. A probe cooled by compressed argon gas is either inserted through the skin of the abdomen or used during surgery to destroy tumors in the liver.
Microwave ablation uses an antenna to discharge microwave radiation into tumor tissue. The tissue is destroyed by the heat that the microwave energy generates via the excitation of water molecules.
Benefits
Radio-frequency ablation, although not a curative procedure, can alleviate the pain and suffering of many liver cancer patients, explains the Society of Interventional Radiology. The procedure does not require general anesthesia, and most patients can go back to their normal activities on the day after treatment. In patients with small tumors, radio-frequency ablation can extend survival time and afford a better quality of life.
Considerations
According to Cancernews, ethanol injection is not an effective technique for liver metastases because they have a hard texture that does not permit the ethanol to uniformly diffuse through the tumor. Therefore, parts of the tumor do not get a complete treatment, and the tumor quickly recurs.
Definitive conclusions about the long-term survival of patients treated with radio-frequency ablation require the completion of more large-scale, controlled clinical trials.
Warnings
Complications of radio-frequency ablation include bleeding and injury to the bile ducts that lead to biliary obstruction. A slight risk of injury to nearby organs is possible, including the lungs and kidneys, depending on the location of the liver tumor.
Technological Advances
Technical improvements made to the electrode that doctors use for radio-frequency ablation have led to an increase in the size of liver tumors that can be treated successfully, notes Cancernews. These improvements include electrode cooling, energy pulsing and electrodes that can be enlarged while inside the tumor.
