"High dose stereotactic body radiotherapy SBRT for men newlydiagnosed with low or intermediaterisk prostate cancer results in shorter treatment times low severe toxicity and excellent cancer control rates according to research presented today at the th Annual Meeting of the American Society for Radiation Oncology ASTRO. The study is the first large multiinstitutional study of SBRT in prostate cancer with longterm followup. Although prostate tumors generally respond well to radiation therapy RT the possibility of radiation exposure to healthy tissue in the genitourinary GU and gastrointestinal GI systems can be of concern. SBRT is an advanced technique that precisely targets high doses of RT to the tumor in a small number fractions simultaneously avoiding surrounding tissue and reducing toxicity to noncancerous cells. The technique has become the standard of care for many nonsurgical lung cancer patients as it limits exposure to the heart and surrounding lungs. When treating tumors in the prostate SBRT avoids the adjacent bladder sex organs and rectum. Singleinstitution studies on the use of SBRT as the primary treatment for prostate cancer have illuminated the treatment as a costeffective and faster alternative to IMRT said Robert Meier MD lead author of the study and a radiation oncologist at Swedish Medical Center in Seattle. Our study is the first to contribute multicenter data that support the use of SBRT as frontline therapy for men with prostate cancer. A total of  men with newly diagnosed prostate cancer were enrolled in the trial at  community regional and academic hospitals across the U.S. Eligible patients had either lowrisk disease CS TTa Gleason  PSA   n   or intermediaterisk disease CS TcTb with either Gleason  and PSA   or Gleason  and PSA . All of the men received SBRT via a nonisocentric robotic platform with an RT dose to the prostate of  Gy administered in five treatment sessions of  Gy each. Intermediate risk patients received a dose of . Gy to the seminal vesicles. Concurrent and adjuvant androgen ablation therapy were prohibited among study participants. Primary outcomes included GU and GI toxicities and relapsefree survival RFS. Researchers measured toxicity using the National Cancer Institutes Common Terminology Criteria for Adverse Events CTCAE version .. Biochemical failure was assessed using the ASTROconsensus and the nadir definitions. Overall survival OS was measured as a secondary outcome for the study. Actuarial OS and RFS were calculated with the KaplanMeier statistical method. Median followup was  months. At five years following SBRT  percent of patients were free from prostate cancer progression. In lowrisk patients the cancer control rates was superior to historical controls. Specifically in the lowrisk group the fiveyear RFS rate was . percent which is superior to the  percent historical comparison DFS control rate p  .. Actuarial fiveyear OS was . percent for the entire cohort. Actuarial fiveyear nadir RFS was . percent for all patients representing . percent of lowrisk and . of intermediaterisk patients. Actuarial fiveyear ASTRO RFS was . percent and . percent for low and intermediaterisk groups respectively. Fewer than two percent of all patients experienced serious side effects in the five years following SBRT. Five grade three GU side effects were reported in four of the  study participants. There were no reported grade four or five toxicities nor any grade three GI toxicities. Between half and twothirds of patients experienced less serious side effects with rates of  and  percent for grade one GU and GI toxicities and rates of  and  percent for grade two GU and GI toxicities respectively. These side effects were usually temporary. Our results illustrate how advanced technology has radically improved our ability to target cancer said Dr. Meier. After following patients for more than five years we found that serious side effects from a brief course of SBRT were uncommon and that cancer control rates were very favorable compared to historical data. Our trial confirms that SBRT may be preferable to other treatment approaches for newlydiagnosed cases of prostate cancer including more aggressive disease. The abstract FiveYear Outcomes from a MultiCenter Trial of Stereotactic Body Radiotherapy for Low and IntermediateRisk Prostate Cancer will be presented in detail during a scientific session at ASTROs th Annual Meeting at  a.m. Eastern time on Monday September  . To speak with Dr. Meier or obtain a copy of the abstract please contact ASTROs media relations team onsite at the Boston Convention and Exhibition Center September  through  by phone at  or by email at pressastro.org mailtopressastro.org. ATTRIBUTION TO THE AMERICAN SOCIETY OF RADIATION ONCOLOGY ASTRO ANNUAL MEETING REQUESTED IN ALL COVERAGE. This news release contains updated data from the study authors.  ABOUT ASTROS ANNUAL MEETINGASTROs th Annual Meeting the nations premier scientific meeting in radiation oncology will be held September   at the Boston Convention and Exhibition Center in Boston. The  Annual Meeting is expected to attract more than  attendees from across the globe including oncologists from all disciplines and members of the entire radiation oncology team. Led by ASTRO president David C. Beyer MD FASTRO the  meeting will feature keynote addresses from Kathleen Sebelius former U.S. Secretary of Health and Human Services Thomas James Lynch Jr. MD Chair and CEO Massachusetts General Physicians Organization and Jason Ragogna general manager SMS and Safety Alliances Corporate Safety Security and Compliance Delta Air Lines Inc. The Presidential Symposium Prostate Cancer Defining Value and Delivering It highlights the meetings theme of Enhancing Value Improving Outcomes and will feature recent practicechanging studies and current developments in valuebased care for prostate cancer. ASTROs fourday scientific meeting will feature a record number of abstracts including  oral presentations  posters and  digital posters in more than  educational sessions and  scientific panels for  diseasesite tracks. For more information about ASTROs th Annual Meeting visit  http For press registration and news briefing information for ASTROs th Annual Meeting visit  http ABOUT ASTROASTRO is the premier radiation oncology society in the world with more than  members who are physicians nurses biologists physicists radiation therapists dosimetrists and other health care professionals who specialize in treating patients with radiation therapies. As the leading organization in radiation oncology the Society is dedicated to improving patient care through professional education and training support for clinical practice and health policy standards advancement of science and research and advocacy. ASTRO publishes three medical journals International Journal of Radiation Oncology  Biology  Physics  http Practical Radiation Oncology  http and Advances in Radiation Oncology  http developed and maintains an extensive patient website RT Answers  http and created the Radiation Oncology Institute  http a nonprofit foundation to support research and education efforts around the world that enhance and confirm the critical role of radiation therapy in improving cancer treatment. To learn more about ASTRO visit  http"