MONDAY, Sept. 28 (HealthDay News) -- Most men are not being told the pros and cons of PSA tests, two new studies find.

Although PSA tests can detect prostate cancer, they can't predict which cancers are aggressive and which are so slow-growing that they don't need to be treated. This leads to overtreatment, which can have immediate consequences, such as impotence and incontinence, and only a tiny increase in survival, researchers say.

"Men in the United States have not been adequately told about the questions regarding the efficacy of prostate cancer screening," said Dr. Otis W. Brawley, chief medical officer at the American Cancer Society, who was not involved in either study.

"They have been misled and over-promised," he said. "People have replaced the hope that prostate cancer screening is beneficial with the message that it is definitely beneficial."

The reports are published in the Sept. 28 issue of the Archives of Internal Medicine.

In the first study, a team led by Dr. Richard M. Hoffman, from the New Mexico VA Health Care System, collected data on 3,010 men 40 and older reached by telephone. Among these men, 375 had undergone or discussed PSA screening in the past two years.

In all, 69.9 percent of the men had discussed screening with their doctor before making a decision. Of these men, 14.4 percent chose not to have the test. In most cases the doctor brought up having the test (64.6 percent), with 73.4 percent recommending it, which was the only point of the discussion, the researchers said.

"Thirty percent of the men said it wasn't even discussed at all," Hoffman said. "Men who did discuss screening heard about the benefits of screening; very few heard about the side effects of screening."

In addition, most men didn't know a lot about prostate cancer, Hoffman said. In fact, only 47.8 percent of men correctly answered any of three questions about prostate cancer risk and screening, Hoffman said.

"This is a very important decision. We think it should be an informed or shared decision, and it's not happening," he said.

The problem with getting the test is that a positive result is going to lead to a biopsy, and only one out of four men who have a biopsy have cancer, Hoffman said.

One reason these discussions aren't taking place is that doctors don't have enough time to discuss screening and prostate cancer in general with their patients, Hoffman said.

Men should educate themselves about the pros and cons of PSA testing, Hoffman said. There are various aids for making such a decision both on the Internet and in print, he said.

In the second report, Kirsten Howard, a senior lecturer in health economics at the University of Sydney in Australia, and colleagues created a statistical model, based on family history, to provide information for men who have low, moderate and high risk for prostate cancer.

"The results of the model predict that benefits and harms of annual PSA screening vary with age and risk level," Howard said.

For example, screening 1,000 men every year from age 40 to 69 only reduces the number who will die from prostate cancer by age 85 from 30 to 28, Howard said.

"So instead of 30 out of the thousand dying from prostate cancer by age 85, only 28 will die of prostate cancer. By the time they are 85, about 640 will have died from all causes of death whether they were screened or not," she said. "Higher risk men have more prostate cancer deaths averted, but also more prostate cancer diagnosed and related harms."

From the model, screened men are about two to four times more likely to be diagnosed with prostate cancer than men who do not get the screening, but death rates from prostate cancer and from other causes are similar in both groups, Howard said.

"The net mortality benefit is small, and this needs to be weighed against the increased chances of being diagnosed and treated for prostate cancer," she said. "Before undergoing PSA screening, men should be aware of the possible benefits and harms, and of their chances of these benefits and harms occurring."

Dr. Michael Pignone, an assistant professor of cancer prevention and control at the University of North Carolina at Chapel Hill and author of an accompanying journal editorial, said that "when you total up the potentially beneficial and potential detrimental consequences of PSA screening, it is not clear that the net effect of PSA screening is beneficial."

Pignone noted that the consequences of prostate cancer treatment, such as impotence and incontinence, occur with treatment. "You suffer the down sides right away," he said. "You only get the benefits, in most cases, far into the future."

Pignone noted that even men with prostate cancer are more likely to die from heart disease or dementia than their cancer. Your chance of dying from prostate cancer is one in a 1,000, while the odds of dying from another cause is 113 in 1,000, he said.

Brawley noted that the American Cancer Society is reviewing its recommendations for PSA screening, and is expected to change them next year.

"Men should know that there are huge question marks, and for some men who are very concerned, perhaps they should get screened. For some men who are less concerned about prostate cancer, perhaps they should not get screened," Brawley said. "But men should not be told that prostate cancer screening is more beneficial than we have evidence to show."

More information

For more information on prostate cancer, visit the American Cancer Society.

SOURCES: Richard M. Hoffman, M.D., M.P.H., New Mexico VA Health Care System, associate professor of medicine, University of New Mexico School of Medicine, Albuquerque; Kirsten Howard, Ph.D., senior lecturer, health economics, University of Sydney, Australia; Michael Pignone, M.D., M.P.H., assistant professor, cancer prevention and control, University of North Carolina, Chapel Hill; Otis W. Brawley, M.D., chief medical officer, American Cancer Society; Sept. 28, 2009, Archives of Internal Medicine

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