(Bloomberg News) PSA screening for prostate cancer used by half of men older than 40 isn't worth the risk of side effects from unnecessary treatment and shouldn't be used to diagnose the disease, a U.S. panel said, affirming its earlier advice.

Scientific studies suggest the number of deaths avoided by screening are "very small" compared with risks from treatment that can include infections, incontinence, erectile dysfunction and death, the U.S. Preventive Services Task Force said. The panel kept its recommendation from October after some doctors and patient groups said discouraging the tests would cost lives.

Prostate cancer was diagnosed in about 250,000 patients last year and caused 33,700 deaths, the task force said. It is the second-most common malignancy among American men. The guidelines may affect whether insurers pay for blood tests measuring PSA, a protein associated at high levels with the disease.

"Many men are being subjected to the harms of treatment of prostate cancer that will never become symptomatic," the panel wrote in a report released yesterday by the Annals of Internal Medicine. "There is convincing evidence that PSA-based screening for prostate cancer results in considerable overtreatment."

The government-sponsored task force is an independent medical advisory group that drew criticism in 2009 for questioning the value of breast-cancer screening in women younger than 50.

In its recommendation, the 16-doctor panel urged against screening for men of all ages, updating a 2008 report that found insufficient evidence to use it in those older than 75. The report cited the slow growth of most prostate tumors as well as false positive rates that may be as high as 80 percent.

Caution For Doctors

While doctors are still free to suggest PSA tests, they should be prepared to discuss the potential downsides, the report said. Community- or employer-offered mass screenings should be discontinued, the group said. The guidelines don't apply to men already diagnosed with the disease.

The findings won the endorsement of the American Cancer Society in an accompanying editorial.

"Americans have been taught for decades to fear all cancer and that the best way to deal with cancer is to find it early and treat it aggressively," said Otis Brawley, the Atlanta-based society's chief medical officer. "As a result, many have blind faith in early detection" with "little appreciation of the harms that screening and medical interventions can cause."

Alternative Methods

Doctors can also detect prostate tumors through digital rectal exams or ultrasound imaging, the report said. Symptoms of the disease include problems urinating, frequent or painful urination, painful ejaculation or a persistent ache in the back, hips or pelvis, according to the National Cancer Institute.

The PSA exam searches for high levels of prostate-specific antigens in the blood. In a 2010 survey, 53 percent of American men older than 40 reported taking the test in the prior two years, according to the U.S. Centers for Disease Control and Prevention.

The panel based its recommendations largely on a U.S. study of 77,000 men who were screened and a European review of 182,000. In the U.S., researchers found no evidence the test reduced deaths. The European trial found the exam lowered the mortality rate. The improvement was due solely to results from Sweden and the Netherlands, while patients in five other countries fared no better after testing, the task force said.

"A substantial percentage of men who have asymptomatic cancer detected by PSA screening have a tumor that either will not progress or will progress so slowly that it would have remained asymptomatic for the man's lifetime," the panel said.

One In 1,000

Screening and early treatment prevent no more than one death in a 1,000, they said. Surgery and radiation to combat tumors, meanwhile, cause at least 200 cases of incontinence and erectile dysfunction per 1,000 patients, while as many as five men in 1,000 die within a month of a prostate operation.

The report ignored problems with the U.S. and European data as well as benefits beyond simply avoiding death, said nine doctors who challenged the findings in a second editorial.

The recommendation "could result in delayed diagnosis of curable cancer in young men who may then present with advanced disease, illness and death," said the physicians, led by William Catalona, a professor of urology at Northwestern University in Chicago. "Elimination of reimbursement for PSA testing would take us back to an era when prostate cancer was often discovered at advanced and incurable stages."

Medicare Policy

Prostate cancer screening remains covered "at this time" under Medicare, the U.S. insurance plan for the elderly and disabled, Ellen Griffith, a spokeswoman for the program, said.

Medicare recommends that men discuss the risks and benefits with their doctors, she said in an e-mail before the release of the recommendations. The task force report doesn't require any action on Medicare's part, she said.

WellPoint Inc., the second-biggest insurer, considers prostate screening "medically necessary" for men from 50 to 75, said Kristin Binns, a spokeswoman, in an e-mail. The Indianapolis-based company will continue to review the medical evidence and "make appropriate decisions as research evolves," she said.

Tyler Mason, a spokesman for UnitedHealth Group Inc., the top private insurer in the U.S., didn't return messages seeking comment. UnitedHealth is based in Minnetonka, Minnesota.

The task force's report should put an end to campaigns for mass screening popularized by celebrities and companies that benefit from "the lucrative business" of testing, said the Cancer Society's Brawley, in his commentary.

"Many advocates for prostate cancer screening have ignored the messages of caution," he said. For patients, "informed or shared decision making is simply not occurring."