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IsoRay's Cancer Fighting Cesium-131 Seeds, Sutures and Seeded Mesh Receive High Marks With Six Abstracts Presented During (ASTRO) the American Society for Radiation Oncology Conference

October 14, 2013 - Richland, WA

IsoRay Inc. (NYSE MKT: ISR) (NYSE Amex: ISR) (, a medical technology company and innovator in seed brachytherapy and medical radioisotope applications, today announced the presentation of clinical findings by numerous medical centers of the successful treatment of cancers and tumors using IsoRay's patented Cesium-131 (Cs-131) seeds, sutured seeds and seed sutured mesh for internal radiation therapy.

IsoRay is extremely pleased to be associated with a growing number of industry thought leaders and medical centers throughout the US. Excerpts from the abstracts presented at ASTRO can be seen below. Note in the following studies, all show Cesium-131's effectiveness in treating tumors compared to other common treatments. Cesium-131 seeds, sutured seeds or mesh were placed within the resected tumor bed at the time of surgery to provide immediate radiation therapy to it and to a margin depth of 5 mm which is dosed to prevent tumor recurrence.

Resection Cavity Dynamics Following Implantation of Cesium-131(Cs-131) Brachytherapy for Resection Brain Metastases Based on CT-Planning
M. Yondorf, L. Nedialkova, B. Parashar, D. Nori, K. Chao, J. Boockvar, S. Pannullo, P. Stieg, T. Schwartz, and A. Wernicke; Weill Cornell Medical College, New York, NY
Purpose/Objective(s): Velocity of tumor shrinkage is one of the factors that correlate with incidence of radiation necrosis (RN), with rapid shrinkage causing significant irradiation of surrounding brain tissue that originally outside the target volume. Our institution has reported the effective use of intra-operative application of Cs-131 brachytherapy for patients with newly diagnosed brain metastases with 0% of clinical RN as compared to I-125 which causes RN 0-26%. In this study, we prospectively assess the resection cavity dynamics with the goal of determining the dose distribution over time and its potential impact on RN.
Conclusions: Resection cavity shrinkage demonstrated in this study over time is negligible, thus potentially explaining 0% incidence of clinical RN in this patient population. Our results are supported by the literature which indicates that no statistically significant volume change occurs up to 33 days after surgery for most patients (Atalar et al). This potentially explains why the short t1/2 of Cs-131 makes an ideal radioisotope as compared to I-125 where resection cavity shrinkage may be of consequence as it only delivers 90% of its intended dose in a 200 day period.

Dosimetric Comparison of Cs-131 Versus I-125 Intraoperative Brachytherapy for Patients With Resected Brain Metastasis Renders Cs-131 More Sparing of Normal Brain Tissue: Clinical Relevance for Prevention of Radiation Necrosis From a Prospective Trial
L. Nedialkova,1 A. Sabbas,1 S. Trichter,1 F. Kulidzhanov,1 B. Parashar,2 D. Nori,2 K. Chao,2 M. Yondorf,2 and A. Wernicke2; 1New York Presbyterian Hospital - Weill Cornell Medical Center, New York, NY, 2Weill Cornell Medical College, New York, NY
Purpose/Objective(s): Cs-131 has significant advantages to I-125 due to its higher dose rate and shorter half life (T 1/2). I-125 implant has been reported in the literature to cause up to 26% incidence of radiation necrosis (RN). This study examines the dosimetric differences between the two radio-isotopes when used as a permanent implant for patients with resected brain metastasis.
Conclusions: In this analysis, we report that Cs-131 exposes less normal brain tissue to radiation, thus providing a dosimetric superiority and subjecting less tissue to RN. Further, with a median follow-up of 10 months, all 24 patients have 100% clinical local control while experiencing 0% incidence of RN.

Interim Results of a Prospective Phase 2 Trial of Pelvic IMRT, Cesium-131 Brachytherapy Boost, Adjuvant Docetaxel Chemotherapy, and Long-term Androgen Ablation for Patients With High-Risk Prostate Cancer
Y. Kwok, M. Ferris, M. Moshe, R. Kataria, and C. Nickerson; University of Maryland Medical Center, Baltimore, MD
Purpose/Objective(s): Despite aggressive therapy more than 50% of patients with high-risk Prostate Cancer fail biochemically. We instituted a phase II protocol which attempts to improve on these results by adding a brachytherapy boost, designed to further increase the prostate dose and docetaxel to address possible systemic disease. The following describes the interim results of patients who have been off of all therapy.
Conclusions: This aggressive, multi-modal therapy incorporating Cs-131 brachytherapy for high risk Prostate Cancer is well-tolerated and produces encouraging disease control. Longer follow-up is needed to assess whether these results are maintained.

Temporal Changes in MRI Edema and Resection Cavity Dynamics Subsequent to Implantation of Cesium-131 (Cs-131) Brachytherapy in Patients With Brain Metastases: A Volumetric Analysis From a Prospective Study
S.P. Lazow, M. Yondorf, I. Kovanlikaya, D. Nori, K. Chao, J. Boockvar, S. Pannullo, P. Stieg, T. Schwartz, and A. Wernicke; Weill Cornell Medical College of Cornell University/New York Presbyterian Hospital, New York, NY
Purpose/Objective(s): Our institution has previously reported the effective use of intra-operative application of Cs-131 brachytherapy for patients with newly diagnosed brain metastases. In this study, we prospectively assess edema and resection cavity dynamics using volumetric analysis of MRI scans following application of Cs-131.
Conclusions: In this study, there is minimal resection cavity shrinkage, and the cavity volume change is not statistically significant even over an extended follow-up period of a median 80 days. This analysis has additionally demonstrated a statistically significant reduction in edema volume between the first post-operative MRI and subsequent MRI scans. Based upon this prospective analysis, there is significant reduction in edema following Cs-131 implantation that is evident at a median 41 days after surgery and maintained throughout the median 80-day follow-up period.

Comparison of Wedge Resection Versus Wedge Resection Plus Cesium-131 Brachytherapy Versus Stereotactic Body Radiation Therapy in Management of Early Stage Lung Cancer Patients That Are Not Candidates for a Standard Lobectomy
B. Parashar,1 S. Arora,1 P. Christos,2 J. Port,3 A. Wernicke,1 D. Nori,1 and K. Chao1; 1Stich Radiation Center, Weill Cornell Medical Center, NY, 2Division of Biostatistics and Epidemiology, Weill Cornell Medical Center, NY, 3Department of Cardiothoracic Surgery, Weill Cornell Medical Center, NY
Purpose/Objective(s): Treatment options for early stage non-small cell Lung Cancer (NSCLC) for patients that cannot undergo lobectomy includes wedge resection (WR), WR plus brachytherapy (WRB) or stereotactic body radiation therapy (SBRT). The purpose of the study was to compare the outcomes for the three treatment options.
Conclusions: Cs131 brachytherapy added to wedge resection significantly improves LC compared to wedge resection alone in early stage NSCLC patients not undergoing lobectomy. Cs131 and SBRT are equivalent and wedge resection alone is inferior in terms of LC. A prospective study comparing the three options is indicated for a final answer regarding the best treatment option for this challenging disease.

Permanent Interstitial Radiation With Cs-131 Implants for Gynecologic Malignancies: Analysis and Results of an Initial 13 Applications
C.E. Wooten, M.E. Randall, P. Aryal, and J. Feddock; University of Kentucky, Lexington, KY
Purpose/Objective(s): Interstitial brachytherapy is an ideal, yet underutilized, treatment modality for small volume gynecological malignancies, especially in circumstances where higher doses of radiation are needed while respecting normal tissue toxicity. Our institution has extensive experience using Au-198 radioactive sources for interstitial brachytherapy. We recently performed the first interstitial implant for a gynecologic malignancy using a newer isotope, Cs-131, which has a more favorable dosimetric profile. This report reviews our initial experience with the Cs-131 radioactive isotope for gynecological patients.
Conclusions: Our series is the first and only to report on clinical outcomes following Cs-131 permanent interstitial implants for gynecologic malignancies. We conclude that Cs-131 seeds are effective in achieving durable local control for small volume gynecologic malignancies.

IsoRay CEO Dwight Babcock says these presentations are just the latest evidence in support of Cesium-131 as a safe and effective treatment of cancerous tumors. These successful studies are what will drive patients and physicians to use Cesium-131 as we continue to promote the Company's pioneering Cesium-131 brachytherapy seeds and liquid isotopes throughout the body. "We continue to advance our domestic and international strategy of creating widespread awareness and adoption of Cesium-131 in hopes that these experiences will ultimately become a standard of care. The exceptional results that have been realized in treating such a wide array of cancers are drawing an increasing number of inquiries from the medical community. We believe Cesium-131's ability to fight cancer and improve the quality of life for the men, women, and children who are battling these devastating cancers distinguishes it from other treatment options."

IsoRay is the exclusive manufacturer of Cesium-131. The pioneering brachytherapy therapy is one of the most significant advances in internal radiation therapy in 20 years. Cesium-131 allows for the precise treatment of many different cancers because of its unrivaled blend of high energy and its 9.7 day half-life (its unequaled speed in giving off therapeutic radiation).

In addition to its CMS codes, Cesium-131 is FDA-cleared and holds a CE mark for international sales in seed form for the treatment of brain cancer, Prostate Cancer, Lung Cancer, ocular melanoma cancer, colorectal cancer, gynecologic cancer, head and neck cancer and other cancers throughout the body. The treatment can be deployed using several delivery methods including single seed applicators, implantable strands and seed sutured mesh, and several new implantable devices.

About IsoRay
IsoRay, Inc., through its subsidiary, IsoRay Medical, Inc. is the sole producer of Cesium-131 brachytherapy seeds, which are expanding brachytherapy options throughout the body. Learn more about this innovative Richland, Washington company and explore the many benefits and uses of Cesium-131 by visiting Join us on Facebook/Isoray ( . Follow us on Twitter @Isoray (

Safe Harbor Statement
Statements in this news release about IsoRay's future expectations, including: the advantages of our Cesium-131 seed and liquid isotopes, whether adoption of Cesium-131 and our other products will continue to increase, whether IsoRay will be able to continue to expand its base beyond Prostate Cancer, whether future studies of treatment of prostate, brain, lung and gynecologic cancers using our products will have favorable results, and all other statements in this release, other than historical facts, are "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995 ("PSLRA"). This statement is included for the express purpose of availing IsoRay, Inc. of the protections of the safe harbor provisions of the PSLRA. It is important to note that actual results and ultimate corporate actions could differ materially from those in such forward-looking statements based on such factors as physician acceptance, training and use of our products, our ability to successfully manufacture, market and sell our products, our ability to manufacture our products in sufficient quantities to meet demand within required delivery time periods while meeting our quality control standards, our ability to enforce our intellectual property rights, whether ongoing patient results with Cesium-131 and our other products are favorable and in line with the conclusions of clinical studies and initial patient results, patient results achieved when Cesium-131 and our other products are used for the treatment of cancers and malignant diseases beyond prostate, whether we, our distributors and our customers will successfully obtain and maintain all required regulatory approvals and licenses to market, sell and use Cesium-131 in its various forms as well as our other products, successful completion of future research and development activities, and other risks detailed from time to time in IsoRay's reports filed with the SEC.

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