Embolization is the injection of substances to try to block or reduce the blood flow to the cancer cells in the liver. The liver is unusual in that it has 2 blood supplies. Most normal liver cells are fed by branches of the portal vein, whereas cancer cells in the liver are usually fed by branches of the hepatic artery. Doctors can exploit this difference to treat the cancer. Blocking the branch of the hepatic artery feeding the tumor helps kill off the cancer cells, whereas most of the healthy liver cells will not be affected because they get their blood supply from the portal vein.
Embolization is another option for patients with tumors that cannot be removed by surgery. It can be used for tumors that are too large to be treated with ablative methods (usually larger than 5 cm across). For some tumors (typically in the 3 to 5 cm range), these treatments may be used together.
This type of treatment typically does not require a hospital stay.
Arterial embolization
Arterial embolization is also known as transarterial embolization (or TAE). In this procedure a catheter (a thin, flexible tube) is put into an artery in the inner thigh and threaded up into the hepatic artery in the liver. A dye is usually injected into the bloodstream at this time to allow the doctor to monitor the path of the catheter via angiography, a special type of x-ray. Once the catheter is in place, small particles are injected into the artery to plug it up.
Embolization also reduces some of the blood supply to the normal liver tissue. This may be dangerous for patients with diseases such as hepatitis or cirrhosis in parts of the liver not affected by cancer.
Chemoembolization
This approach, also known as transarterial chemoembolization (or TACE) combines embolization with chemotherapy. This is done either by coating the small particles with chemotherapy drugs before injection, or by giving chemotherapy through the catheter directly into the artery, then plugging up the artery. Studies are looking to see if chemoembolization is more effective than embolization alone.
Radioembolization
This newer technique combines embolization with radiation therapy.
In the United States, this is done by injecting small radioactive beads (called microspheres) into the hepatic artery. Once infused, these beads lodge in the blood vessels near the tumor, where they give off small amounts of radiation to the tumor site for several days. This treatment has been approved by the FDA and is available through several cancer treatment centers. Long-term data on its use isn't yet available, but it has been shown to help tumors shrink.
Another way of delivering radiation to the tumor is by using a radioactive oil, known as I-131 lipiodol, which is also infused directly into the hepatic artery. This type of radioembolization is now being studied. It is not available in the United States at this time.
Side effects of embolization
Possible complications after embolization include abdominal pain, fever, infection in the liver, gallbladder inflammation, and blood clots in the main blood vessels of the liver. Serious complications are uncommon, but they are possible.
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