Selective Internal Radiation Therapy (SIRT)

Selective internal radiation therapy (SIRT) is a targeted treatment for liver tumors that delivers millions of tiny radioactive beads called SIR-Spheres Y-90 resin microspheres directly to the liver tumors. SIR-Spheres Y-90 resin microspheres are approved in the U.S. for the treatment of inoperable colorectal liver metastases in combination with hepatic arterial chemotherapy using FUDR (floxuridine). These liver tumors are also known as secondary liver metastases because the cancer cells have spread to the liver from the primary colon or rectal tumor.

Who Is a Good Candidate for SIRT?

SIRT is only suitable for patients who have liver tumors where either the liver is the only site of disease or the liver is the major site of disease. SIRT has no effect on tumors outside the liver.

Before SIRT can be offered as a treatment option for patients, there are a number of other factors that have to be considered by your doctor. Most importantly, you need to have a sufficiently healthy liver that is working satisfactorily. This is usually determined by a simple blood test.

Watch this video to learn more about SIRT.

How Is the SIRT Procedure Performed?

The interventional radiologist makes a small puncture, usually into the femoral artery near the groin or the radial artery near the wrist. Your physician will determine which approach is best for your treatment plan. A small flexible tube, known as a catheter, is then guided through the artery into the liver. The SIR-Spheres Y-90 resin microspheres are administered through this catheter. The whole procedure may take about 90 minutes. Your doctor will discuss with you medication and anesthesia that may be used during the procedure.

How Do SIR-Spheres® Y-90 Resin Microspheres Work?

The SIRT procedure enables radiation – which is often used to treat cancer – to be sent directly into the liver tumors by using the tumor’s blood supply. The normal liver tissue takes about 75% of its blood supply from the portal vein that flows from the intestine while liver tumors receive about 90% of their blood supply from the hepatic artery. SIR-Spheres Y-90 resin microspheres are targeted directly at the liver tumors via the hepatic artery, so exposure to the remaining healthy liver tissue is minimized.