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Proton Radiation Fails to Impress in Prostate Cancer Study
By Charles Bankhead, Staff Writer, MedPage Today Published: September 26, 2008 Reviewed by Zalman S. Agus, MD; Emeritus Professor University of Pennsylvania School of Medicine. BOSTON, Sept. 26 -- Proton radiation for early prostate cancer had an acceptable tolerability profile but produced little evidence of a "gee whiz" impact to support its cost, according to preliminary results from a phase I/II clinical trial. Two-thirds of patients had acute genitourinary or gastrointestinal toxicity, and a third had late GU/GI toxicity, Anthony Zietman, M.D., of Harvard and Massachusetts General Hospital, reported at the American Society for Therapeutic Radiology and Oncology meeting. Although most of the toxicity was grade 2 in severity, the overall profile provided little reason for enthusiasm. "The bottom line is that the treatment was safe, it was reasonably well tolerated, but probably no better tolerated than any other form of radiation that we give," Dr. Zietman said. "I think it's true that if I were looking at this data for the first time, I would say, 'What's the big deal? I didn't see a home run here,'" he added. The preliminary findings, which did not include treatment outcomes, reflected what Dr. Zietman characterized as the "exuberant maelstrom" surrounding the evolution of proton radiation. Development of the technology and facilities might be outpacing the accumulation of supporting clinical data, he said. Six proton radiation centers have opened in the United States, and a dozen others are in various stages of development. Dr. Zietman said a center can cost upwards of $150 million to build. Given the huge upfront capital expenditure, hospitals may find themselves under the gun to ramp up patient throughput right away. Proton radiation has unquestioned value for treatment of certain rare cancers, said Dr. Zietman. However, the technology has yet to demonstrate any advantages over other forms of radiation therapy for common malignancies, such as lung and prostate cancer, where proton radiation centers would recoup the capital investment. "The problem is that most patients in the United States treated with proton beam are treated for prostate cancer," he said. "It's the economic driver of the proton avalanche." At the ASTRO meeting, Dr. Zietman reported safety data on 85 patients with localized prostate cancer treated with proton radiation. The patients had localised disease and PSA values 15 ng/mL. The primary endpoint was GI/GU toxicity and morbidity. At a median follow-up of two years, the rates of acute GI/GU toxicity were 50% grade 1, 14% grade 2, and 1% grade 3. Late toxicity was grade 2 severity in 25% of patients, grade 3 in 7%, and grade 4 in 1% (one case of hemorrhagic cystitis and rectal ulcer). The two-year actuarial risk of grade 3+ toxicity was 6.1%. No patients died. Follow-up has been too brief for assessment of secondary endpoints, said Dr. Zietman. Dr. Zietman disclosed that he is a member of the speakers bureau and has received honoraria from Ismar Medical. Primary source: International Journal of Radiation Oncology - Biology - Physics Source reference: Zietman AL, et al "A prospective phase I/II study usingproton beam radiation to deliver 82GyE to men with localized prostate cancer: preliminary results of ACR 0312" Int J Radiat Oncol Biol Phys 2008; 72(1 Suppl):S77. Abstract 169. http://www.medpagetoday.com/MeetingCoverage/ASTRO/tb/11076 Copyright MedPage Today, LLC. All Rights Reserved. We hope you visit http://www.medpagetoday.com every day for the latest in medical news
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