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Benefit of prostate tests still in doubt after study


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POSTED: Wednesday, March 18, 2009

A 17-year national prostate cancer study, including 5,999 Hawaii men, hasn't resolved a controversy over the pros and cons of screening for this disease.

Follow-up data on the participants showed no difference in prostate cancer deaths of men screened versus those in a “;usual care”; group, said Dr. Lance Yokochi, principal investigator for the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial at the Pacific Health Research Institute.

The “;usual care”; participants had no screening as part of the trial, “;but we can't tell people not to get tests,”; he said.

The U.S. Preventive Services Task Force concluded there wasn't enough evidence to say whether prostate cancer screening in men under age 75 is beneficial or harmful. It recommended against such screening in men 75 and older.

The results of the study — the largest of its kind in the United States — were reported online today in the New England Journal of Medicine to coincide with a presentation at a European Association of Urology meeting in Stockholm, Sweden. They'll be printed in the journal's March 26 issue.

The national trial included women as well as men, to determine also if lung, colorectal and ovarian cancer screenings make a difference in the death rate, Yokochi said in an interview.

Nationally, 76,693 men age 55 to 74 participated in the trial at 10 centers, and 38,343 were randomly assigned to screening with annual prostate-specific antigen tests for six years and digital rectal exams for four years. The blood tests measure the levels of PSA, an enzyme produced by the prostate that can be associated with a tumor.

The other men were randomly assigned to “;usual care”; with no recommendations for or against screening. But annual surveys taken of those men showed more were getting prostate cancer screening tests each year — up to 52 percent by the last year surveyed.

A total of 10,854 Hawaii men and women participated in the study, Yokochi said. Of the 5,999 men, 3,001 were randomly assigned to prostate screening tests. Others were in the usual-care group.

More prostate cancers were found in the annual screening, but that didn't result in fewer deaths up to 10 years after screening began, the researchers found.

Most men will develop prostate cancer some time in their life, Yokochi said, but usually the cancer is slow-growing and men die of another cause before it's a threat. An aggressive type may occur at a younger age, but that's not the norm, he said.

The benefits of the PSA test used to detect signs of prostate cancer have been debated. Proponents say it has saved thousands of lives, while others say men diagnosed with prostate cancer would be better off not knowing they have the low-risk disease because of emotional trauma.

Also, they say the prostate enzyme is sensitive to changes and could draw false positives.

Some organizations say men should have yearly digital rectal exams by age 40 and PSA screening by 50, Yokochi said. “;The main reason for the study was to see if this is justified,”; he said.

Both groups had few prostate cancer deaths, which the study attributes to good treatment in the United States.

Fifty men in the screening group and 44 in the usual-care group died of prostate cancer seven years after screening began. After 10 years, there were 92 deaths in the screening group and 82 in the usual-care group.

“;Thus, there was no detectable mortality benefit for screening versus usual care,”; the study reported.