Study Supports Intensity Modulated Radiation Therapy for Prostate Cancer

Researchers from the University of North Carolina at Chapel Hill have found that the most widely used radiation treatment – intensity modulated radiation therapy (IMRT) – is better at controlling localized prostate cancer than the older conformal radiation therapy (CRT) and is just as effective as proton therapy, which is a newer technique. The study, published in the Journal of the American Medical Association, compared outcomes and side effects of these 3 different types of radiation.

Co-author Ronald C. Chen, MD, MPH said, “This study supports the use of IMRT as the current standard radiation technique for prostate cancer.”

Chen said almost all men receiving radiation treatment for localized prostate cancer in 2002 received CRT, but today more than 95% of the Medicare population receives IMRT – an almost complete adoption of the newer method without a lot of data to support it.

Chen said IMRT is both more sophisticated and more expensive. It delivers radiation from multiple angles using beams of different strengths, targeting a higher dose to the prostate and less to surrounding organs. Proton radiation, which is even newer and even more expensive, uses a different type of particle to deliver the radiation. In theory this should let doctors deliver more radiation to the prostate and do less damage to nearby normal tissues, but very little research has been published directly comparing patient outcomes with the different techniques.

The study examined information from Medicare patients with localized prostate cancer – prostate cancer that had not spread – using the Surveillance, Epidemiology and End Results (SEER) database from 2000 through 2009.

Researchers found that men treated with IMRT were about 20% less likely than those getting CRT to receive additional cancer therapy later on, which indicates their cancer was less likely to return. They were also less likely to have side effects including hip fracture and gastrointestinal problems such as rectal bleeding or diarrhea. But they were more likely to have erectile dysfunction.

Compared to proton therapy, IMRT patients had a 34% lower risk of gastrointestinal problems. There were no significant differences in rates of additional cancer therapy or erectile dysfunction.

The researchers write, “Proton therapy is a high-profile, high-cost prostate cancer treatment. Since 2007, multiple proton facilities have been built, and direct-to-consumer advertising is likely to lead to a substantial increase in use.” They conclude that proton therapy did not provide additional benefit for prostate cancer patients in their study and call for more research to compare the effectiveness of proton therapy vs. IMRT.

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master’s-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Intensity-Modulated Radiation Therapy, Proton Therapy, or Conformal Radiation Therapy and Morbidity and Disease Control in Localized Prostate Cancer. Published in the April 18, 2012 issue of the Journal of the American Medical Association (Vol. 307, No. 15). First author: Nathan C. Sheets, MD, University of North Carolina at Chapel Hill.

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