Y-90 treatment, also called radioembolization, is a minimally invasive procedure that delivers targeted radiation directly to liver tumors. Tiny radioactive microspheres are injected into the blood vessels feeding the tumor, where they lodge in the tumor’s blood supply and emit radiation over several days. The treatment is used primarily for liver cancers that can’t be surgically removed, including both cancers that started in the liver and cancers that spread there from other organs.
How Y-90 Works Inside the Liver
The procedure relies on millions of microscopic beads, each loaded with the radioactive isotope yttrium-90. A doctor threads a catheter through the groin artery up to the hepatic artery, the main blood vessel feeding the liver, and releases the microspheres directly into the branches supplying the tumor. Because liver tumors get most of their blood from the hepatic artery (while healthy liver tissue relies more on the portal vein), the microspheres preferentially concentrate in and around the tumor.
Once lodged in the tumor’s tiny blood vessels, the microspheres emit beta radiation with an average tissue penetration of just 2.5 millimeters and a maximum reach of 11 millimeters. This short range is the key advantage: the radiation destroys tumor cells while largely sparing surrounding healthy tissue. Yttrium-90 has a half-life of about 64 hours, meaning 94% of the radiation dose is delivered within the first 11 days. After that, the yttrium decays into stable, non-radioactive zirconium, and the spent microspheres remain harmlessly embedded in the liver.
Although the microspheres do physically block small blood vessels (that’s the “embolization” part of the name), the tumor-killing effect comes primarily from radiation injury rather than cutting off blood supply.
Who Is a Candidate
Y-90 was originally developed for hepatocellular carcinoma (HCC), the most common type of primary liver cancer. It has since expanded to treat liver metastases from a range of cancers. Colorectal cancer that has spread to the liver is the most frequent use after HCC. Other cancers treated include gastric, breast, neuroendocrine, pancreatic, renal cell, and esophageal cancers, as well as melanoma, when they’ve metastasized to the liver and surgery isn’t an option.
Not everyone qualifies. Your liver needs to be functioning well enough to tolerate the radiation. A total bilirubin level above 2.0 mg/dL (a marker of liver function), significant fluid buildup in the abdomen, or severely reduced physical functioning are all relative contraindications. Patients with advanced underlying liver disease, particularly those in the most severe category of liver dysfunction, face a significantly increased risk of radiation-induced liver injury and are generally steered toward other options.
The Mapping Session Before Treatment
Before the actual Y-90 procedure, you’ll undergo a planning session sometimes called a “mapping” procedure. A doctor performs a test run using a different radioactive tracer injected through the same catheter route. This scan serves two purposes: it maps the blood vessel anatomy feeding your tumor, and it measures how much of the injected material might escape from the liver into the lungs through abnormal connections between arteries and veins within the tumor.
Lung shunting is one of the major safety concerns because too much radiation reaching the lungs can cause radiation pneumonitis, a serious inflammatory reaction. There are specific dose limits: for glass microspheres, the lung dose can’t exceed 30 Gy in a single treatment or 50 Gy cumulatively, while for resin microspheres, lung shunting above 20% disqualifies a patient. If your mapping scan shows acceptable results, the treatment itself is typically scheduled one to two weeks later.
Glass vs. Resin Microspheres
Two types of Y-90 microspheres are commercially available. Glass microspheres (TheraSphere) and resin microspheres (SIR-Spheres) differ in their size, the amount of radioactivity per individual sphere, their density, and how much they block blood flow. The choice between them depends on the clinical scenario, including tumor type, tumor size, and how much embolic effect the treating physician wants. Both are well-established and widely used, and the decision is typically made by the interventional radiology team based on your specific situation.
What the Procedure Day Looks Like
The treatment itself is performed by an interventional radiologist, usually under moderate sedation rather than general anesthesia. A catheter is inserted through a small puncture in the groin and guided using real-time X-ray imaging to the precise hepatic artery branch feeding the tumor. The microspheres are then slowly infused. The entire procedure typically takes one to two hours, and most people go home the same day or the next morning.
Because the radiation has such a short range and decays quickly, the amount of external radiation you emit after treatment is very low. You won’t need to be isolated from family members the way some other radiation therapies require, though your care team will give you specific guidance about any short-term precautions.
Recovery and Side Effects
Fatigue is the most common aftereffect, often lasting a week or two. Many people also develop a cluster of symptoms called post-embolization syndrome, which typically starts within three days of the infusion. This includes nausea, vomiting, loss of appetite, abdominal pain, and low-grade fever. Most people with these symptoms start feeling better within about a week.
The more serious risk is radiation-induced liver disease, which can develop weeks after the procedure. In rare cases, liver function deteriorates progressively, with rising bilirubin levels and signs of liver failure appearing around six weeks post-treatment. This is why baseline liver function matters so much in patient selection. The liver biopsy findings in these cases resemble damage from blocked blood outflow, with tissue death concentrated around the central veins of the liver.
How Effective Is Y-90
Outcomes vary depending on the type of cancer, the extent of disease, and how well your liver is functioning at baseline. In a study of patients with advanced hepatocellular carcinoma, the objective response rate (meaning the tumor visibly shrank) was 31%, and the disease control rate, including patients whose tumors stopped growing, was 68%. Median overall survival for the full group was 13.6 months.
The patients who benefited most were those with good baseline liver function and physical fitness whose cancer was confined to the liver. This group had a median survival of 21.8 months, nearly double that of patients with poorer functional status. These numbers reflect a population with advanced-stage cancer that had no surgical options, so the survival figures represent what the treatment adds on top of what would otherwise be a poor prognosis.
Y-90 Compared to Chemoembolization
The main alternative to Y-90 for inoperable liver tumors is chemoembolization (TACE), which delivers chemotherapy drugs directly to the tumor through its blood supply while also blocking the feeding vessels. A phase II randomized trial comparing Y-90 to chemoembolization using drug-eluting beads found that Y-90 provided superior tumor control and survival in patients with early or intermediate hepatocellular carcinoma, with a similar safety profile between the two approaches. Serious adverse events occurred in 39% of Y-90 patients compared to 53% in the chemoembolization group, though this difference was not statistically significant. Thirty-day mortality was 0% in the Y-90 group and 8.3% in the chemoembolization group.
Y-90 also tends to require fewer treatment sessions and involves less post-procedure pain compared to chemoembolization, which often requires hospital stays of several days per session. For many patients, this translates to less overall disruption to daily life during treatment.