Liver Cancer

Novel radiation technique aids some who are unable to have transplant

Dr. Paz-Fumagalli and his team prepare to release radioactive glass spheres into a patient's artery during a radioembolization procedure.

Enlarge

For liver cancer patients who are not candidates for transplant or other lifesaving surgery, there's a new option that offers improved quality of life and survival time.

Radioembolization or intra-arterial brachytherapy is a form of radiation therapy that delivers high doses of cancerkilling radiation directly to liver tumors. The procedure is better tolerated than other forms of intra-arterial liver cancer treatments, and it may be the best therapy for patients whose options are limited. The procedure is performed in an outpatient setting and it takes about an hour to complete.

Patients are given a local anesthetic and mild intravenous sedation. Physicians insert a catheter into the femoral artery in the leg and under X-ray guidance advance it to an artery that branches off from the hepatic artery, one of the two primary vessels that bring blood to the liver. Then the physicians inject tiny glass spheres containing a radioactive material into the artery. Normal blood flow carries these spheres, smaller in diameter than a human hair, into ever smaller arteries that branch off from larger ones. The particles eventually become lodged at the tumor, where they deliver a high dose of radiation.

"The technique is a clever way of exploiting the differences in blood supply between the liver tumor and normal liver tissue," says Dr. Ricardo Paz-Fumagalli, a Mayo Clinic interventional radiologist. He works with Mayo Clinic radiation oncologists to deliver the therapy.

Normal liver tissue receives about three-fourths of its blood supply from the portal vein and only about one-fourth from the hepatic artery and its branches. Liver tumors, on the other hand, get most of their life-sustaining blood supply from the hepatic artery and absorb a greater proportion of microspheres.

"So if you give a treatment through the arteries, it more specifically hits the tumor," Paz-Fumagalli says, "and the normal liver is relatively spared."

The microspheres release radiation over 10 days to two weeks, saturating the tumor with a higher dose than is generally tolerated if it were given by the normal external beam method.

"The type of radiation used penetrates a very thin layer of tissue, about 2-to -3 millimeters on average, so very little radiation will escape and expose other tissues or other people to it," says Paz-Fumagalli.

The Yttrium-90 radiation deteriorates fairly quickly.

"By the time two weeks go by, you have very little radiation left," Paz-Fumagalli says. "It's very safe. It's very highly concentrated to the tumor yet doesn't go very far. For that reason the body can tolerate these doses of radiation quite well."

But if such high doses of radiation were carried by blood flow to the lungs, stomach or bowel, it would cause severe damage. For that reason, detailed imaging tests are done before treatment to make sure there isn't too much blood flowing to the other organs from the hepatic artery.

Surgery and liver transplant are the main treatments for liver cancer, but those options aren't usually available to all patients with large or numerous tumors, tumors that have spread to other organs or with poor liver reserve. If surgery isn't an option, the prognosis is usually poor. For these patients, radioembolization therapy enables doctors to improve their quality and quantity of life. In some cases, it may be used to shrink a tumor to prepare a patient who is a candidate for a liver transplant, which can be a cure for hepatocellular carcinoma.

This story first appeared in the July 2006 issue of The Mayo Clinic Checkup, a complimentary newsletter available to anyone interested in the latest news from Mayo Clinic in Jacksonville, Fla.