Understanding Y-90 Radioembolization
Y-90 radioembolization (also called selective internal radiation therapy, or SIRT) is a form of targeted radiation treatment for liver tumours. It works by delivering millions of tiny radioactive microspheres (beads) directly into the blood vessels that feed the tumour. These microspheres lodge in the small arteries within and around the tumour and emit radiation over a short range, destroying cancer cells while largely sparing the surrounding healthy liver tissue.
The “Y-90” refers to Yttrium-90, the radioactive isotope embedded in the microspheres. Yttrium-90 emits beta radiation, which travels only a few millimetres in tissue. This short range is what makes the treatment so targeted: the radiation affects the tumour and its immediate surroundings but does not reach far enough to damage distant healthy tissue.
Which Liver Cancers Can Be Treated?
Y-90 radioembolization is used for several types of liver cancer, both primary and secondary.
Hepatocellular Carcinoma (HCC)
HCC is the most common primary liver cancer and frequently develops in patients with underlying liver disease such as cirrhosis or chronic hepatitis. Y-90 is used when surgical removal is not possible due to tumour size, location, or the patient’s liver function. It can also serve as a bridge therapy while patients wait for a liver transplant, helping to control the tumour during the waiting period.
Liver Metastases from Colorectal Cancer
The liver is a common site for colorectal cancer to spread. When chemotherapy alone is not controlling liver metastases, Y-90 radioembolization can be added to the treatment plan. It may also be used when patients cannot tolerate further systemic chemotherapy.
Other Liver Metastases
Liver metastases from neuroendocrine tumours, breast cancer, and other primary cancers may also be considered for Y-90 treatment, depending on the clinical situation. The decision is made by a multidisciplinary team that includes oncologists, hepatologists, interventional radiologists, and nuclear medicine physicians.
How the Treatment Works
The logic behind Y-90 radioembolization is rooted in the liver’s unique blood supply. Normal liver tissue receives about 75 percent of its blood from the portal vein and only about 25 percent from the hepatic artery. Liver tumours, however, are different: they receive almost all of their blood supply from the hepatic artery. By injecting the radioactive microspheres through the hepatic artery, the treatment preferentially targets the tumour.
The microspheres are too large to pass through the tiny blood vessels within the tumour, so they become permanently lodged there. Once in place, they emit beta radiation continuously for about two weeks (the half-life of Yttrium-90 is approximately 64 hours), delivering a concentrated dose of radiation directly to the cancer cells.
The Procedure: Step by Step
Pre-Treatment Assessment
Before Y-90 treatment, a thorough assessment is performed. This includes blood tests to evaluate liver function, imaging (CT or MRI) to assess the tumour, and a planning angiogram.
The planning angiogram is a critical step. A catheter is inserted through the femoral artery in the groin and guided to the hepatic artery under fluoroscopic (X-ray) guidance. During this procedure, the interventional radiologist maps the blood vessel anatomy supplying the liver and identifies any vessels that might carry microspheres to unintended locations (such as the stomach or intestines). These vessels are blocked (embolised) if needed.
A small amount of a surrogate tracer (Tc-99m MAA) is then injected through the catheter to simulate where the Y-90 microspheres will go. A nuclear medicine scan performed after this injection confirms that the microspheres will reach the tumour and not shunt excessively to the lungs or other organs.
Treatment Day
The actual Y-90 treatment usually takes place one to two weeks after the planning session. The procedure is similar to the planning angiogram: a catheter is guided to the hepatic artery, positioned precisely, and the Y-90 microspheres are slowly injected. The entire procedure typically takes one to two hours.
Most patients receive a local anaesthetic at the catheter insertion site and mild sedation. General anaesthesia is not usually required.
Post-Treatment
After the procedure, patients are monitored for a few hours and often go home the same day or the following day. A post-treatment scan (PET CT or SPECT CT with Bremsstrahlung imaging) is performed to confirm that the microspheres have been deposited in the intended location.
Recovery and Side Effects
One of the advantages of Y-90 radioembolization compared to external beam radiation or systemic chemotherapy is the relatively mild side effect profile for many patients.
Common side effects include:
- Fatigue: This is the most frequently reported side effect and can last for a few weeks.
- Mild abdominal discomfort: Some patients experience a dull ache in the right upper abdomen for a few days.
- Low-grade fever: A mild fever in the first few days is not uncommon.
- Nausea: Usually mild and manageable with standard medications.
More significant complications are uncommon but can occur. These include radiation-induced liver disease (RILD), gastric or duodenal ulceration (if microspheres reach the stomach), and biliary complications. The careful pre-treatment planning described above is specifically designed to minimise these risks.
Most patients return to their normal daily activities within one to two weeks.
How It Fits Into a Broader Treatment Plan
Y-90 radioembolization is rarely a standalone treatment. It is typically part of a broader treatment strategy that may include chemotherapy, targeted therapy, immunotherapy, or surgery. In some cases, Y-90 treatment can shrink a tumour enough to make surgical removal possible when it was not before (this is called downstaging).
The treatment can be repeated if needed, and in some cases, different sections (lobes) of the liver are treated in separate sessions.
All treatment decisions are made collaboratively by a multidisciplinary team. Your oncologist, hepatologist, and nuclear medicine physician will discuss whether Y-90 is appropriate for your specific situation and how it fits into your overall care plan.
Speaking With Your Doctor
If you or a family member has been diagnosed with a liver tumour and you have heard about Y-90 radioembolization, discuss it with your treating physician. They can assess whether you are a suitable candidate based on your tumour type, liver function, and overall health.
To learn more about how this treatment is performed, visit our page on Y-90 intra-arterial therapy.