Sirtex Presents SIR-Spheres(R) Microspheres Data at the American Brachytherapy Society 2006 Meeting; Meeting marks debut of microspheres therapy for liver cancer at annual event.

PHILADELPHIA -- New research on Sirtex's SIR-Spheres(R) microspheres will be presented at the 2006 American Brachytherapy Society's annual meeting held May 10-12 in Philadelphia. Dr. Andrew Kennedy, co-medical director of Wake Radiology Oncology Services in Cary, N.C., will discuss findings of two studies involving SIR-Spheres microspheres for treatment of advanced liver cancer. Dr. Kennedy's presentation marks the first time microspheres therapy has been featured at the ABS meeting. Sirtex's SIR-Spheres microspheres are the only FDA-approved microspheres therapy for metastatic liver cancer.

Dr. Kennedy's first poster presentation is a retrospective review of 18 patients who received SIR-Spheres microspheres for carcinoid tumors. Standard use of microspheres therapy for carcinoid tumors is to apply once, typically to a single lobe, followed with treatment to the second lobe one month later. Dr. Kennedy evaluated the outcome of treating all tumors during each treatment, a process known as whole liver therapy. A second and third treatment was given to control large lesions.

Following brachytherapy, participants were monitored with regular laboratory and imaging studies. Eighty-nine percent of patients responded to the treatment, with a median follow-up period of 27 months. Researchers concluded that whole liver and multiple treatments with microspheres brachytherapy are safe and produce a high response rate, even with large tumors.

"We are grateful to Dr. Kennedy for his ongoing microspheres research," says Dr. David Cade, medical director for Sirtex. "Carcinoid tumors are historically difficult to treat. By offering a whole liver approach, this data suggests we are able to treat patients more effectively and increase response rates."

Dr. Kennedy also will present a poster analyzing the current dosing guidelines for SIR-Spheres microspheres. His team compared the current dose planning recommendations with his own dosing formula based on tumor volume and prescribed amount of radioactivity. Though Dr. Kennedy's formula resulted in 20-30 percent less radioactivity, it enabled a more consistent delivery of microspheres. The reduced activity lowered the risk of radiation-induced liver damage, but did not decrease tumor response.

"Choosing the appropriate microspheres dose is critical," Dr. Kennedy says. "We use this formula in our practice and have had no severe complications or reactions from dosing. The goal is to deliver the most effective dose to the tumor site, but not prescribe too much activity, which can result in liver toxicity or additional disposal concerns for the treating team."

Abstracts on both research papers will be available in the May issue of the journal Brachytherapy. The publication is the official journal of the American Brachytherapy Society.

About SIR-Spheres Microspheres

SIR-Spheres(R) microspheres are radioactive polymer spheres that emit beta radiation. Physicians insert a catheter through the groin into the hepatic artery and deliver millions of microspheres directly to the tumor site. The SIR-Spheres microspheres target the liver tumors sparing healthy liver tissue. Approximately 55 physicians in the United States use Sirtex's SIR-Spheres microspheres in more than 60 medical centers.

About Sirtex

SIR-Spheres microspheres were developed in the 1980s in Australia and gained FDA approval in March 2002. Sirtex has obtained regulatory approval to market SIR-Spheres microspheres in the United States, European Union, Israel and Australia. The product is marketed in New Zealand, Hong Kong, Malaysia, Singapore and Thailand. For more information, visit www.sirtex.com.