Data on intra-arterial radioembolization of unresectable primary and metastatic liver tumors with yttrium-90 microspheres show the procedure is safe and effective. Though palliative in scope, the outpatient technique offers survival benefits to some patients and could turn into a bridge for liver transplant.
Surgical resection and transplantation remain the top treatment options for patients with hepatocellular carcinoma or metastatic liver disease. Unfortunately, only about one-fifth of patients can undergo these procedures. Most undergo transarterial chemoembolization (TACE), external radiation, or chemotherapy, which may lead to nasty side effects or diminishing results after recurring treatment. Thermal ablation, on the other hand, has not yet proved effective on large lesions or extensive liver disease.
The potential toxic effects of systemic therapy outshine its alleged benefits. That may explain the booming reliance on local and regional treatments such as radioembolization in the U.S., said Dr. Riad Salem, director of interventional oncology at Northwestern Memorial Hospital in Chicago, at the April Society of Interventional Radiology meeting in Toronto.
Two FDA-approved drugs carrying the beta ray-emitting yttrium-90 have gained the attention of U.S.-based interventionalists: TheraSphere glass beads and SIR-Spheres resin spheres. The first is used to treat hepatocellular carcinoma, and the second hepatic colorectal metastases that have failed to respond to systemic chemo. The procedure delivers via catheter into the hepatic artery a bolus of millions of microspheres that irradiate tissue within a 2.5-mm range. Patients may tolerate doses up to 150 Gy for single and 268 Gy for repeated infusions. Y-90 has a half-life of 64 hours.
Salem and colleagues recently reported on the longest follow-up study to date on one of the largest populations treated with TheraSphere. Investigators enrolled 140 patients with hepatocellular carcinomas who underwent 238 outpatient infusions. They stratified patients according to their degree of disease involvement using the Okuda, Child-Pugh, and low/high-risk Y-90 classification categories. They measured patients' baseline liver function on the day of treatment and performed clinical follow-up at one month and 90-day intervals thereafter. The researchers found that, after radioembolization treatment, low-risk patients survived well over two years, compared with a median of 258 days for high-risk patients.
German investigators led by Dr. Tobias F. Jakobs from the University of Munich reported similarly encouraging data on 34 patients treated with SIR-Sphere for extensive unresectable hepatic metastases. Although researchers found no remissions, a statistically significant number of patients showed some level of response or stable disease at three, six, and nine-month follow-up. Jakobs presented the findings at the SIR meeting.
As Y-90 microspheres make solid strides to become yet another therapeutic alternative for nonoperable liver tumors, researchers contemplate other possibilities. For some patients, for instance, treatment with Y-90 could help control and stabilize the diseased liver to make it amenable for transplantation (J Gastrointest Surg 2006 Mar;10[3]:413-416).
Caveats, however, include high costs and risks. The total technical fees for the procedure can average $130,000 per patient, which seems expensive compared with thermal ablation or TACE treatment at around $20,000 per single procedure. Most patients typically undergo multiple ablation or chemoembolization, however, and total technical fees average almost $170,000 per patient.
Interventionalists must follow careful technical guidelines before each procedure. Blood supply to the liver and other gastrointestinal organs should not interconnect to avoid unwanted delivery of toxic particles that can cause several morbidities, including gastric ulcer and even death, said Dr. Sun Ho Ahn, an assistant professor of radiology at Brown University Medical School.
