Embolization therapy for liver cancer

Embolization is the injection of substances to try to block or reduce the blood flow to 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, but it leaves most of the healthy liver cells unharmed because they get their blood supply from the portal vein.

Embolization is an option for some patients with tumors that cannot be removed by surgery. It can be used for tumors that are too large to be treated with ablation (usually larger than 5 cm across). For some tumors (typically in the 3 to 5 cm range), these treatments may be used together. Embolization does reduce some of the blood supply to the normal liver tissue, so it may not be a good option for some patients whose liver has been damaged by diseases such as hepatitis or cirrhosis.

This type of treatment typically does not require a hospital stay.

Arterial embolization

Arterial embolization is also known as trans-arterial embolization (or TAE). In this procedure a catheter (a thin, flexible tube) is put into an artery through a small cut 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 help the doctor 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.

Chemoembolization

This approach, also known as trans-arterial 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. Brand names for these beads include TheraSphere^® and SIR-Spheres^®. Once infused, the beads lodge in the blood vessels near the tumor, where they give off small amounts of radiation to the tumor site for several days. The radiation travels a very short distance, so its effects are limited mainly to the tumor. Long-term data on this treatment isn't yet available, but it has been shown to help tumors shrink.

Side effects of embolization

Possible complications after embolization include abdominal pain, fever, nausea, infection in the liver, gallbladder inflammation, and blood clots in the main blood vessels of the liver. Serious complications are not common, but they are possible.