**5.5 Yttrium microspheres**

Treatment with Yttrium glass microspheres occurs when a catheter is placed in the hepatic artery and the Therasphere vial, which is comprised of silica containing Yttrium, is rapidly injected. The intent is to deliver 125–150 Gy (12,500 –15,000 rads) of radiation to the tumor or tumors. In a study of 65 patients treated from August 2000 to August 2003, 42 patients (64.6 %) had a significant decrease in tumor size within 4 months. The median survival among Okuda stage I patients was 649 days in historical comparison to a median of 244 days. The median survival among Okuda stage II patients was 302 days in historical comparison to a median of 64 days (Carr, 2004). A benefit of this procedure is that it is generally better tolerated than TACE. Drawbacks are potential radiation to other organ systems and elevated cost. Also, it is also contraindicated in patients with severe liver synthetic dysfunction. To be eligible for treatment, a patient must be relatively wellcompensated, with a bilirubin < 2.0 mg/dL, creatinine < 2.0 mg/dL, platelets > 60 K/L, a lung shunt < 16%, and ECOG performance < 2 (Carr, 2004).

### **5.6 External Beam Radiation Therapy**

External Beam Radiation Therapy (EBRT) occurs when radiation is delivered to a tumor after the placement of fiducial markers, which are markers are implanted via sterilized needles under ultrasound or CT guidance. Some clinical reports have demonstrated response rates to EBRT ranging from 80-87.5 for small HCC. EBRT may achieve a 10-12 log decrease in tumor, compared to up to 6 logs associated with chemotherapy. An advantage is that EBRT can be delivered to multiple lesions regardless of the proximity of the tumor or tumors to major hepatic vessels or bile ducts. Another advantage is that it is less costly than procedures such as treatment with Yttrium glass Microspheres: an estimation of EBRT is \$4,047 for treatment and consultation (Wigg, 2010).
