Yttrium-90 Radioembolization — Targeted Liver Radiation Therapy

Yttrium-90 (Y-90) radioembolization is a specialised form of brachytherapy performed by interventional radiologists. Normal liver tissue derives the majority of its blood supply from the portal vein, whereas liver tumours receive their blood primarily from the hepatic artery. Radioembolization exploits this unique circulatory dynamic.

During the procedure, an interventional radiologist threads a microcatheter through the femoral or radial artery directly into the hepatic arterial branches supplying the tumour. Millions of tiny resin or glass microspheres embedded with Y-90—a high-energy beta-emitting radioisotope—are infused. These spheres lodge within the microvasculature of the tumour, delivering intense, localised internal radiation over a short distance while minimising collateral damage to healthy liver parenchyma.

Liver tumours are often resistant to standard external radiation because the healthy liver cannot tolerate large radiation doses without severe toxicity. Y-90 radioembolization overcomes this obstacle by delivering intense radiation internally. It can shrink tumours, delay disease progression, alleviate symptoms, and occasionally downstage inoperable tumours so that curative surgical resection or liver transplantation becomes viable.

Before the procedure, patients undergo a diagnostic angiography and a Technetium-99m macroaggregated albumin (Tc-99m MAA) scan to evaluate vascular anatomy and ensure the beads will not escape into the lungs or stomach. Baseline liver function tests (bilirubin, albumin, INR) and tumour markers such as alpha-fetoprotein (AFP) or carcinoembryonic antigen (CEA) are monitored before and after treatment.

Y-90 radioembolization is primarily used for hepatocellular carcinoma (primary liver cancer) and intrahepatic cholangiocarcinoma (bile duct cancer). It is also extensively employed to treat liver metastases originating from other primary cancers, particularly metastatic colorectal cancer, neuroendocrine tumours, and, less frequently, breast cancer with liver-dominant spread.

Radioembolization can be deployed as a primary locoregional therapy, a bridge to liver transplantation, or a palliative intervention combined with systemic treatments. Following the procedure, patients are monitored with contrast-enhanced CT or MRI to evaluate tumour shrinkage, necrosis, and changes in vascularity according to modified response criteria.