Results of a five-year study evaluating the tolerability, efficacy and survival rates of Selective Internal Radiation Therapy (SIRT), also known as radioembolization, using SIR-Spheres? (Sirtex) microspheres in patients with liver metastases from breast cancer that are refractory to chemotherapy, suggest that the therapy is effective and well-tolerated. The study was led by Roberto Cianni, M.D., interventional radiologist at Santa Maria Goretti Hospital in Latina, Italy. The results of the study were presented during the annual meeting 47th Annual Meeting of the American Society of Clinical Oncology (ASCO), taking place in Chicago Friday, June 3 ? Tuesday, June 7 2011.

Selective Internal Radiation Therapy (SIRT), also known as radioembolization, is a novel treatment for inoperable liver cancer that delivers high doses of radiation directly to the site of tumors. In a minimally-invasive treatment, millions of radioactive SIR-Spheres microspheres are infused via a catheter into the liver where they selectively target liver tumors with a dose of internal radiation up to 40 times higher than conventional radiotherapy, while sparing healthy tissue.

Increased life expectancy
Clinical trials have confirmed that liver cancer patients treated with SIR-Spheres microspheres have response rates higher than with other forms of treatment, resulting in increased life expectancy, greater periods without tumor activity, and improved quality of life. SIRT has been found to shrink liver tumors more than chemotherapy alone.

The study observed 49 patients undergoing treatment for breast cancer liver metastases. All eligible patients received radioembolization using SIR-Spheres (Yttrium-90 resin microspheres), and follow-up CT and PET exams were scheduled in eight and 12-week increments.

Complete response/partial response
Using Response Evaluation Criteria in Solid Tumors (RECIST) criteria, researchers noted complete response/partial response (CR/PR) in 24 patients (49%), stable disease (SD) in 17 patients (35%), and progressive disease (PD) in eight patients. Technical success rate and effectiveness, estimated at three months, were 98 percent and 80 percent, respectively. Side effects graded by Common Terminology Criteria on Adverse Events were represented by one grade 4 hepatic failure, one grade 2 gastritis and one grade 2 cholecystitis. The median survival and the progression-free survival calculated were 354 days (11.8 months) and 279 days (9.3 months), respectively.

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?Our primary objective was to provide prolonged disease control for patients with liver-dominant metastatic breast cancer that was refractory to chemotherapy, since there are few effective treatment options available,? Dr. Cianni said. ?The results of our study with SIR-Spheres are very encouraging, with 84% of the patients experiencing disease stabilization or tumor shrinkage and a prolonged progression free survival period. The treatment was also well-tolerated, which is an important consideration for patients.?

Decrease in tumor size
Researchers concluded that radioembolization using SIR-Spheres microspheres is effective and well-tolerated in patients with liver metastases from breast cancer. Response to therapy was supported by the decrease in tumor size and activity.

?Breast cancer remains a significant disease, affecting over 200,000 women in the U.S. and 450,000 in Europe,? said Nigel Lange, CEO, Sirtex Medical Europe GmbH. ?Unfortunately, breast cancer spreads to the liver at some point in around one in four women and is a major cause of morbidity and mortality. The results of this study are very promising, particularly considering that the patients were heavily pre-treated and were no longer responding to chemotherapy.?

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