Radioembolization

Radioembolization, or selective internal radiation therapy (SIRT), is a minimally invasive cancer treatment for liver tumors. It delivers radioactive yttrium-90–laden microspheres via selective catheterization of the hepatic artery so that tumors receive high radiation doses while surrounding liver tissue is relatively spared.

Microspheres are available in resin and glass forms; dosimetry depends on formulation. Before treatment, angiography maps arterial supply to tumors and protects non-target vessels. A tracer test with technetium-99m MAA estimates lung shunt and potential extrahepatic deposition.

Indications include unresectable hepatocellular carcinoma, liver-dominant colorectal metastases, and some neuroendocrine tumors, as well as bridging or downstaging prior to surgery or transplantation. It may be used in patients who are poor candidates for transarterial chemoembolization.

The procedure typically occurs on an outpatient basis. After catheter placement, a therapeutic activity of Y-90 is delivered, with post-procedure imaging to confirm distribution. Common short-term effects resemble flu-like symptoms; most patients recover. Serious risks include radiation-induced liver disease, biliary injury, and, with significant lung shunt, radiation pneumonitis.

Outcomes vary; response rates and survival depend on tumor type, extent of disease, and liver function. Y-90 radioembolization is an established option within multidisciplinary liver cancer care, providing local tumor control and potential downstaging in selected patients.