Radioembolization with Sirspheres or Theraspheres is a newer technique used to treat both primary and metastatic cancer that has spread to the liver. Prior to treatment, patients undergo an outpatient screening arteriogram. Two weeks following the screening test, a catheter is fed into the artery going to the liver, and the spheres are infused. Certain tumor types such as hepatocellular carcinoma, ocular melanoma, colon cancer and breast cancer and other less common malignancies can be treated with this technique. In this procedure, radioactive particles are infused into the liver treating the tumors with internal radiation therapy. Treatments are typically done on an outpatient basis.