What is TheraSphere®


How does TheraSphere® work?

TheraSphere® consists of millions of tiny glass microspheres containing radioactive yttrium-90 ( Y90). 1,9 The microspheres have a mean diameter of 20–30 micrometers (about one-third of the width of a human hair) and are delivered directly to liver tumors.1 Treatment with TheraSphere® is commonly referred to as transarterial radioembolization (TARE) or selective internal radiation therapy (SIRT).

How is TheraSphere® administered?

TheraSphere® is injected into the hepatic artery (the blood vessel that supplies oxygenated blood to the liver) through a small, flexible, hollow tube (known as a catheter) that is inserted in the upper leg.1 The tiny radioactive glass microspheres flow directly into the liver tumor and become permanently lodged in the small blood vessels of the tumor.11 The radiation destroys tumor cells from within the tumor, with minimal impact to the surrounding healthy liver tissue.4,11,12 Although the microspheres will continue to emit radiation for some time after TheraSphere® treatment, radiation levels decrease to about 15% of initial levels after one week and to insignificant levels soon thereafter.1 

What happens after treatment with TheraSphere®?

TheraSphere® treatment is typically an outpatient procedure that does not require hospitalization.7 It is well tolerated, with side effects that are normally milder than with many other liver cancer treatments.3,5,7 Because the procedure is directed to the liver tumor, there is minimal impact to healthy tissue.4,11,12 After treatment, most TheraSphere® patients are able to undergo further treatment options because the procedure does not block the vessels of the liver.7 

What are the side effects of TheraSphere®?


When can TheraSphere® be used?

TheraSphere® may be used to:

  • Treat hepatocellular carcinoma (HCC), a type of cancer that starts in the liver, which cannot be removed by surgery1
  • Treat liver cancer while waiting for a liver transplant7,8

TheraSphere® has been approved by the U.S Food and Drug Administration (FDA) under a Humanitarian Device Exemption (HDE) based on demonstrated safety and probable clinical benefit.1 

Who is TheraSphere® suitable for?

TheraSphere® is suitable for patients in whom either the liver is the only site of disease or the liver is the major site of disease.1 The effects of TheraSphere® on tumors outside the liver has not yet been studied.

Before TheraSphere® can be offered as a treatment option, several factors will be taken into consideration to minimize side effects and optimize therapy to the liver, including liver performance, medical history and the liver blood flow.1 Do not hesitate to ask your doctor or nurse about the tests they will perform.
For more information on what to expect from TheraSphere® treatment, including pre-treatment planning and post-treatment instructions, please see your Guide


FDA = U.S. Food and Drug Administration; HCC = hepatocellular carcinoma; HDE = Humanitarian Device Exemption; RFA = radiofrequency ablation; SIRT = selective internal radiation therapy; TARE = transarterial radioembolization; Y90 = yttrium- 90