Yttrium-90 Internal Radiation
Yttrium-90 is a therapeutic device that delivers radiation directly to tumors in the liver using tiny beads. The tiny beads (or intrahepatic microspheres) measure one third the diameter of a human hair, and are embedded with a radioactive element called yttrium90.
Millions of these microspheres can be injected into the bloodstream, then guided into the hepatic artery, the liver's main blood vessel. When they arrive in the liver, the radiation-laden spheres get stuck within the smaller blood cells that sustain tumors, rather than the larger vessels feeding healthy tissue. This is because tumor blood vessels are smaller in size than normal blood vessels, therefore deliver radiation directly to tumors while sparing healthy tissue.
As a result, the treatment is relatively nontoxic — ideal for patients who have chronic hepatitis or cirrhosis and therefore may not have great hepatic reserve. Yttrium-90 treatment appears to have a low level of side effects compared with traditional radiation or chemotherapy. And because Yttrium-90 radiation poses little danger to others, patients don't have to remain in the hospital under any kind of isolation technique — which allows them to interact with family and friends soon after the procedure. Another advantage is that a limited number of treatments may be capable of achieving the same therapeutic efficacy as multiple treatments with chemotherapy or chemoembolization.
Types of Yttrium-90 Therapies
SIR-Spheres®
At the UPMC Liver Cancer Center, SIR-Spheres® are currently being used as treatment for patients with unresectable colon/rectal metastases to the liver who have failed to respond to systemic chemotherapy. More than 20 patients have been treated with this form of therapy.
The SIR-Spheres® are biocompatible radioactive microspheres that emit yttrium-90. They are delivered by a percutaneous approach into the hepatic artery feeding the tumors in the liver. A single dose of FUDR chemotherapy is injected into the liver during the same treatment session as the SIR-Spheres®.
Patients that receive either TheraSphere® or SIR-Spheres® treatment for liver tumors generally spend one evening in the hospital and are discharged home the next morning.
TheraSphere®
At the UPMC Liver Cancer Center, TheraSphere® is currently being used as initial treatment for certain patients with unresectable hepatocellular carcinoma (HCC). Over the last six years at the Liver Cancer Center, more than 110 patients with HCC have been treated with this form of therapy.