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Study: 17,000 more men diagnosed with prostate cancer too late for treatment without PSA test

A key government panel has raised concerns about the reliability of the P.S.A. blood test, which is used to diagnose prostate cancer. Dr. Jon LaPook reports the test is not nearly as helpful as previously thought.

(CBS News) Do PSA tests for prostate cancer actually boost men's survival against the deadly disease?

The controversial question has been up for recent debate among doctors and patients following the May release of new government guidelines that recommended against the blood test that looks for high levels of prostate-specific antigen (PSA) as a measure of cancer risk.

Now a new study finds without the screening tests, 17,000 more men would learn too late that they have the deadliest, metastatic form of the prostate cancer - an incurable form of the disease.

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Earlier this year, the U.S. Preventive Services Task Force, a panel of medical advisors that issue government guidelines, said healthy men should skip the PSA test. They argued that a positive result could do more harm than good if it picks up a tumor that may be too slow-growing to ever cause a problem. In those cases, the radiation and surgery to remove the affected prostate could result in major side effects that are worse than if the tumor was left alone.

The panel in its review found that for every 1,000 men who get a PSA test, 30 to 40 will develop erectile dysfunction, two will experience a major heart problem and one will develop a potentially deadly blood clot. The task force however found that for every 1,000 men, at most one will avoid dying from prostate cancer as a result of a positive PSA test.

Those guidelines have been criticized by some medical groups, including the American Urological Association, which calls the recommendation a "disservice to American men" because there is no comparable screening for prostate cancer available.

For the new study, published in the American Cancer Society's journal Cancer, researchers wanted to find out what would happen without PSA testing.

Researchers at the University of Rochester Medical Center reviewed patient data from before routine PSA testing started, from 1983 to 1985, and compared it to data from 2006 to 2008, what researchers considered the start of the era of widespread PSA testing. The researchers in particular wanted to know about patients who had advanced prostate cancer - which spreads to other areas - at the time of diagnosis. Metastatic prostate cancer is often considered incurable however if left untreated, significant symptoms may occur.

After reviewing the 2008 data, the researchers found that 8,000 men had metastasized prostate cancer at the time of their diagnosis. Using a mathematical formula based on pre-PSA metastatic prostate cancer rates, the researchers determined that there would be approximately 25,000 cases of metastatic prostate cancer diagnosed. That's an additional 17,000 cases, three times more than the actual number of cases discovered in 2008, suggesting the tests are catching cancers early which may become deadly.

"Our findings are very important in light of the recent controversy over PSA testing," Dr. Edward Messing, chair of the urology department at the University of Rochester Medical Center in New York, said in a press release. "Although there are trade-offs associated with the PSA test and many factors influence the disease outcome, our data clearly indicate that not doing the PSA test will result in many more men presenting with far advanced prostate cancer."

"Almost all men with clinically apparent metastases at initial diagnosis will die from prostate cancer," he added.

Dr. Michael LeFevre, a professor of family medicine at the University of Missouri who served as co-chair of the U.S. Preventive Services Task Force criticized the study to WebMD.

"This study is not a randomized trial, and the results don't tell us much about whether screening reduces a man's chances of having metastatic prostate cancer," LeFevre said. "Since death from prostate cancer will nearly always be preceded by metastatic disease, one would expect a significant decline in metastatic disease to be accompanied by a significant reduction in deaths. But that is not what the clinical trials show."

Prostate cancer is the most common cancer among men and the second-leading cause of cancer death in men. Nearly 242,000 men will be diagnosed with prostate cancer in 2012, the National Cancer Institute estimates, and more than 28,000 will die.

The American Cancer Society recommends that men make an informed decision about whether to take a PSA test after discussing the risks and benefits with their doctor.