Ablation and Embolization to Treat Gastrointestinal Stromal Tumors

If a gastrointestinal stromal tumor (GIST) has spread to the liver, treatments such as ablation and embolization might be used, especially if surgery can't be done to remove the tumors.  

Ablation

Ablation is the destruction of tumors using extreme heat or cold, or using chemicals. It can sometimes be used to destroy GISTs that have spread as no more than a few small tumors in the liver. Because ablation often destroys some of the normal tissue around the tumor, it might not be a good choice for treating tumors near important structures like major blood vessels, the diaphragm (the thin breathing muscle above the liver), or major ducts in the liver.

There are several types of ablation:

• Radiofrequency ablation (RFA), which uses high-energy radio waves to heat the tumor and destroy cancer cells
• Ethanol (alcohol) ablation, where concentrated alcohol is injected directly into the tumor to kill cancer cells
• Microwave thermotherapy, where microwaves transmitted through a probe placed in the tumor are used to heat and destroy the cancer cells
• Cryosurgery (cryotherapy), which destroys a tumor by freezing it using a thin metal probe. This method sometimes requires general anesthesia (you are in a deep sleep and not able to feel pain)

What to expect

Usually, you don't need to stay overnight in the hospital for this type of treatment. Ablation can often can be done without surgery by inserting a needle or probe into the tumor through the skin. The needle or probe is guided into place with ultrasound or CT scanning. This might be done with general anesthesia (you are in a deep sleep) or with conscious sedation (you are awake but sleepy and should not feel any pain). Sometimes, though, to be sure the treatment is aimed at the right place, it is done during surgery.

Possible side effects of ablation

Possible side effects after ablation therapy include abdominal (belly) pain, infection in the liver, and bleeding into the chest cavity or abdomen. Serious complications are uncommon, but they can happen.

Embolization

Embolization is a procedure in which the doctor injects 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. 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 does reduce some of the blood supply to the normal liver tissue, so it might not be a good option for some patients whose liver has already been damaged by diseases such as hepatitis or cirrhosis.

What to expect

The main type of embolization used to treat GISTs that have spread to the liver is arterial embolization (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 see 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 can also be done by injecting tiny radioactive spheres into the hepatic artery (radioembolization), or by giving chemo directly into the artery just before plugging it up (chemoembolization). But it’s not clear that either of these techniques is better than TAE.  

This procedure might be done with general anesthesia (where you are in a deep sleep) or with conscious sedation (where you are awake but sleepy and should not feel any pain). Typically, you won't have to stay overnight in the hospital for an embolization procedure.

Possible side effects of embolization

Possible complications after embolization include abdominal (belly) pain, fever, nausea, infection in the liver, gallbladder inflammation, and blood clots in the main blood vessels of the liver. Because healthy liver tissue can be affected, there is a risk that liver function will get worse after treatment. This risk is higher if a large branch of the hepatic artery is embolized. Serious complications are not common, but they are possible.