Selective Internal Radiation Therapy (SIRT) is a treatment for advanced liver cancer in which the radiation is delivered directly to tumor sites in the liver using millions of microscopic radioactive spheres caller SIR-Spheres. The average number of particles implanted is between 30 and 60 million and 94 percent of the radiation is delivered in 11 days.
SIR-Spheres are delivered through a small tube (catheter), which is placed into an artery and threaded into the liver artery to the site of the tumor. The spheres lodge in the small blood vessels of the tumor. The spheres irradiate and destroy the tumor while most of the normal liver tissue remains relatively unaffected. Once SIR-Spheres are implanted into the liver, the microscopic spheres stay permanently in the liver.
SIRT with SIR-Spheres is used for the treatment of unresectable (unable to be removed with surgery) metastatic liver tumors from primary colorectal cancer (cancer that has spread to the liver). SIRT is given with adjuvant intra-hepatic artery chemotherapy (in addition to the SIRT therapy, chemotherapy is delivered into the hepatic artery).