This page was reviewed under our medical and editorial policy by

Henry Krebs, MD, Interventional and Diagnostic Radiologist

This page was reviewed on December 2, 2022.

Doctors may recommend that those diagnosed with liver cancer, whether it began in the liver or spread there from other malignancies, undergo a type of radiation therapy called radioembolization. This treatment slows the growth of tumors in the liver and may reduce its symptoms.

The majority of patients with the most common form of liver cancer, hepatocellular carcinoma, aren’t diagnosed until the disease has reached an advanced stage—past the point when surgical removal of tumors and other treatments may be recommended. For some patients, radioembolization shrinks tumors to the point where a liver transplant becomes a possibility.

Oncologists also use this procedure to treat other types of cancer that have spread or metastasized to the liver. Secondary cancer—one that has spread from another organ, including the colon and the breast—may result in tumors that respond well to this form of liver-directed therapy. Sometimes, radioembolization is used in combination with chemotherapy.

How does it work?

In this procedure, an Interventional radiologist delivers very tiny radioactive beads through the hepatic artery, which is where the tumors almost always get their blood supply. Specifically, these microscopic glass or resin beads, called microspheres, are filled with the isotope yttrium-90, or Y-90 for short. They emit ionizing radiation designed to kill cancer cells. They are then carried by the bloodstream to the tumors and tend to spare healthy tissue in the liver, which mostly derives its blood supply from the portal vein.

The radiation’s effects may continue to work for many weeks, even after the radiation can no longer be measured outside the body. The harmless beads remain in the body.

Before the procedure

Ahead of the procedure, you may undergo blood tests to measure your blood-clotting and kidney functions. You may be asked about current medications and advised to avoid taking blood-thinning drugs, including aspirin and some herbal supplements.

The arteries in the upper abdomen are mapped using a diagnostic test called an angiogram. This helps doctors visualize the blood vessels supplying the tumor. Locating the branches of the artery feeding the tumor and injecting them with the radioactive beads are designed to reduce damage to healthy liver tissue.

During this pre-procedure angiogram, radio-opaque contrast material is injected into the bloodstream and shows up on X-rays that outline the blood vessels. You’ll be sedated or placed under general anesthesia for the procedure and may feel slight discomfort when the local anesthetic is injected at the catheter insertion site. Occasionally, the injection of the contrast dye may cause a warm feeling.

During the procedure

On the day of the procedure, you'll be given medication to help you relax. You may feel slight discomfort when an intravenous (IV) line for sedation is placed into a vein.

The procedure starts with another angiogram, which serves as a roadmap for the radiologist. This involves gaining access to the arterial system via a wrist or groin artery. To prevent the radioactive beads used in radioembolization from flowing into the tissues of the stomach and duodenum (the first section of the small intestine), tiny metal coils may be used to block blood vessels from the liver to those areas. A similarly sized radioactive but non-therapeutic bead will be injected and traced by nuclear medicine imaging to calculate how much of the radioactive material could possibly end up in the lungs.

For the radioembolization, a thin catheter, about an eighth of an inch in diameter, is inserted and threaded to the tumor site. Once the catheter reaches the tumor, the microbeads are injected. The dose amounts to about a half teaspoon. The catheter is removed, and pressure is held over the catheter insertion site for an hour or so.

After the procedure

Radioembolization generally is performed on an outpatient basis, so most patients go home the same day. To reduce exposing other people to radiation, you may be asked to avoid contact as much as possible for a few days, especially with children and pregnant women. For about at least three days afterward, you’ll need to sleep alone and not sit next to anyone for more than two hours.

Side effects and risks

All forms of embolization may block blood flow to nearby healthy tissue, with the possibility of causing damage. The chances rise with the size of the artery blocked. For that reason, liver function may suffer as a result, and the procedure may not be suitable if you have a liver heavily damaged by hepatitis or cirrhosis.

Still, radioembolization is considered minimally invasive and fairly painless, and it’s designed to spare healthy liver tissue. It causes fewer side effects than standard radiation therapy.

Common side effects after the procedure include:

  • Fatigue
  • Nausea
  • Pain
  • Low-grade fever, usually lasting a week or two

Less common but serious complications range from fluid buildup in the abdomen (ascites) to the microbeads flowing to the stomach or duodenum and causing an ulcer to the rare possibility of developing an inflamed pancreas or a liver abscess.

Infection remains a risk, though very small, as with any surgical procedure.

Although an angiogram is considered low risk, an allergic reaction may occur and the contrast dye used may lead to kidney failure in rare instances.


After the procedure, your care team may schedule a follow-up visit including blood tests and further imaging.

Radioembolization improves the health of 70 to 95 percent of patients with all types of liver cancer, according to the Radiological Society of North America and the American College of Radiology. As many as 95 percent of patients with colorectal cancer that spread to the liver and 97 percent of patients with neuroendocrine tumors have shown benefits from this therapy.

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