Leading Medical Centers Join Growing Number of Locations Offering IsoRay's Prostate Cancer Treatment Proxcelan™ Brachytherapy Seeds

Business Wire, August 9, 2007

University of Pittsburgh Medical Center and Arizona Oncology Services Offer Brachytherapy Seed Breakthrough

RICHLAND, Wash. -- University of Pittsburgh Medical Center (UPMC), and Arizona Oncology Services (AOS) are two of the latest leading medical facilities offering prostate cancer patients the breakthrough Proxcelan[TM] brachytherapy seeds (Cesium-131). Proxcelan is a proprietary product of IsoRay Medical[TM] - a wholly owned subsidiary of a public company, IsoRay, Inc. ("IsoRay") (AMEX:ISR), based in Richland, WA. Proxcelan has Food & Drug Administration 510(k) clearance for treating prostate cancer and other malignancies.

"With independent studies now being presented on a regular basis focusing on the therapeutic benefits of Proxcelan, we expect to see centers adopting Proxcelan on an increasing basis," said IsoRay Chairman and CEO Roger Girard.

Proxcelan is the newest isotope used in brachytherapy seed treatment for prostate cancer, and the first breakthrough in more than 20 years. It is a powerful, aggressive new medical isotope offering patients faster delivery dosage, better quality of life and improved tumor penetration than is available with other isotopes currently being used.

Prostate seed brachytherapy is a common procedure in which seeds containing isotopes emitting low-dose radiation (LDR) are implanted in and around a cancerous tumor to kill cancer cells. Approximately 60,000 procedures are conducted each year in the United States.

"UPMC and AOS have chosen to offer prostate cancer patients the highly effective, strategically targeted treatment that Proxcelan offers," said IsoRay Medical National Sales Director Eric Knipfer. "With the increased clinical evidence and expansion of the sales team, we expect to see an even greater number of centers adopting Proxcelan."

University of Pittsburgh Medical Center

The University of Pittsburgh Medical Center (UPMC), located in Pittsburgh in Western Pennsylvania, is a renowned academic facility. It is a top recipient of research funding from the National Institutes of Health (NIH). UPMC serves 29 western Pennsylvania counties, and treats an estimated 4 million patients a year. It encompasses 19 hospitals and 40 cancer centers with 75 affiliated oncologists.

UPMC Cancer Centers include more than 30 office-based medical oncology practices and regional cancer centers that provide the highest standard of care for cancer patients throughout the tri-state area. UPMC Cancer Centers work in tandem with the University of Pittsburgh Cancer Institute to carry out its mission as a premier National Cancer Institute-designated Comprehensive Cancer Center dedicated to conducting ground-breaking research in cancer prevention, detection, diagnosis and treatment.

Arizona Oncology Services

Arizona Oncology Services (AOS) focuses on achieving the highest standards in radiation oncology care. AOS has been based in the Phoenix area since 1981 and serves over 4,000 patients a year.

"We believe Proxcelan represents the next leap forward in isotopes for prostate cancer brachytherapy," said Dr. Daniel Reed of AOS. "Patients respond very well to treatment and it allows them to return to normal activities quickly."

AOS is a nationally recognized leader in many radiation techniques, including prostate seed implants, accelerated partial breast therapy and stereotactic radiosurgery. AOS was the first in Arizona to perform these treatments, as well as introducing Intensity Modulated Radiotherapy (IMRT), Image Guided Radiotherapy (IGRT), lung brachytherapy, and radiolabelled monoclonal antibody therapy to the state.

Increasingly, prostate cancer patients and their doctors who decide on seed brachytherapy choose Proxcelan because of its significant advantages over Palladium-103 and Iodine-125, two other isotopes currently in use. These advantages include:

Higher Energy

Proxcelan has a higher average energy than any other commonly used prostate brachytherapy isotope on the market. Energy is a key factor in how uniformly the radiation dose can be delivered throughout the prostate. This is known as homogeneity. Early studies demonstrate Proxcelan implants are able to deliver the required dose while maintaining good homogeneity across the gland itself and potentially reducing unnecessary dose to critical structures such as the urethra and rectum. [1]

Shorter Half-Life

Cesium-131 has the shortest half-life of any prostate brachytherapy isotope at 9.7 days. Cesium-131 delivers 90% of the prescribed dose to the prostate in just 33 days compared to 58 days for Palladium-103 and 204 days for Iodine-125. The short half-life of Cs-131 reduces the duration of time during which the prostate receives the irritating effects of the radiation. Early studies demonstrate Cesium-131 is well tolerated with minimal to moderate urinary symptoms that resolve relatively rapidly, within approximately 4-8 weeks. [1]

Higher Biologically Effective Dose

Another benefit to the short half-life of Proxcelan is what is known as the "biological effective dose" or BED. BED is a way for health care providers to predict how an isotope will perform against slow versus fast growing tumors. Studies have shown Cesium-131 is able to deliver a higher BED across a wide range of tumor types than either Iodine-125 or Palladium-103. Although prostate cancer is typically viewed as a slow growing cancer it can present with aggressive features. Cesium-131's higher BED may be particularly beneficial in such situations. [2]