TheraSphere is a radiotherapy treatment for hepatocellular carcinoma (HCC) that consists of millions of microscopic, radioactive glass microspheres (20–30 micrometres in diameter) being infused into the arteries that feed liver tumors.
It is currently approved as a Humanitarian Device, meaning effectiveness has not been proven, for patients as a neoadjuvant to surgery or transplantation by the U.S. Food and Drug Administration and is being used at a number of clinical centers in the United States.
The Therasphere package insert contains a Black Box warning concerning 5 Pre-treatment high risk factors associated with serious adverse events resulting in 11/12 deaths.
[1] Following embolization of the yttrium-90 glass microspheres in tumorous liver tissue, the beta radiation emitted provides a therapeutic effect.
The microspheres are unable to pass through the vasculature of the liver due to arteriolar capillary blockade and are trapped in the tumor.