Proton beam radiation, heavily promoted by facilities that perform the treatment, also came with a higher risk of certain side effects compared to intensity-modulated radiation therapy (IMRT), researchers found.

"This paper is the strongest evidence yet that proton beam (therapy) is not only not better, but probably not as good as IMRT," said Dr. Matthew Cooperberg, a urologist from the University of California, San Francisco, who didn't participate in the new research.

The findings suggest that men have multiple radiation options when it comes to treating early, localized prostate cancer.

Though not covered in the new study, their options also include surgery -- or getting no treatment at all and waiting to see how the disease progresses, researchers said.

Dr. Ronald Chen of the University of North Carolina at Chapel Hill and his colleagues used data from a nationwide cancer registry covering treatment records for men insured by Medicare who were diagnosed with prostate cancer starting in 2000.

At that time, less than one percent of prostate cancers that hadn't spread beyond the gland were treated with IMRT, a minimally-invasive treatment meant to limit damage to the surrounding organs. The rest were treated conformal radiation, the previous standard of care.

By 2008, almost 96 percent of men got the high-dose, targeted radiation.

Intensity-modulated radiation was tied to an approximately 10 to 20 percent lower risk of stomach problems and hip fractures compared to conformal radiation therapy, which exposes more organs around the prostate to radiation. But it also came with a 12 percent higher risk of erectile dysfunction.

Over the course of each year after radiation, 2.5 percent of men who'd received IMRT needed more cancer treatment -- suggesting their disease came back -- compared to 3.1 percent of men in the traditional-radiation group.

That was based on records of close to 13,000 men age 66 and older.

In a smaller analysis, Medicare patients who got proton beam therapy, the most high-tech type of radiation offered, didn't fare much better or worse than those who had IMRT -- except that proton-treated men had more stomach-related side effects.

HUNDREDS OF MILLIONS IN COSTS

The use of both of those technologies has driven up the cost of prostate cancer treatment by hundreds of millions of dollars, the researchers wrote in the Journal of the American Medical Association.

But with conformal radiation fading from popularity, patients' radiation choice now tends to come down to IMRT versus proton therapy -- which is available at far fewer cancer centers because of the technology required.

Researchers said that proton beam facilities can cost $100 million or more to build. A round of proton beam radiation treatment costs insurers up to $100,000 per patient, while IMRT is billed at about $50,000.

"Here we have more expensive therapy that is not proven to give a better outcome," said Dr. Eric Klein, a prostate cancer researcher at the Cleveland Clinic, who didn't take part in the new study.

Researchers agreed that policymakers, including those that decide how much Medicare will pay for various treatments, should reevaluate the evidence for cancer outcomes -- including whether proton beam therapy is worth its hefty price tag.

"There's a trend in this country of adopting newer, costly, promising treatments, without very much evidence to prove they're better," Chen told Reuters Health.

"What our data provides the patients is evidence that IMRT is a good prostate cancer treatment," he said. Until more rigorous studies are available, "That's the type of radiation that they should seek."

WATCHFUL WAITING?

Another perfectly good option for men with early prostate cancer is not to get treatment at all, but to wait and see whether the cancer grows or doesn't cause any harm, researchers said.

"Many men with early disease, especially men who are older, likely don't need treatment," said Dr. W. Robert Lee, a radiation oncologist at the Duke University School of Medicine in Durham who wasn't involved in the new study.

"Active surveillance really plays a very important role," he told Reuters Health.

Cooperberg told Reuters Health that if men find their doctor pushing one treatment option, especially if it's a high-tech radiation option, they should seek outside opinions and think about their priorities -- in terms of what side effects they can put up with and the chance of needing more serious treatment.

"Prostate cancer is very much a disease of options," Lee said.

SOURCE: bit.ly/hwxtTL Journal of the American Medical Association, online April 17, 2012.

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