Studies: PSA test doesn't save lives

March 20, 2009 8:44:31 AM PDT
Screening for prostate cancer doesn't necessarily save lives, and any benefits can come at a high price, according to two, big long-awaited studies. The findings are unlikely to end the debate over the usefulness of routine testing.

The two studies - one in Europe and one in the United States - reached different conclusions. In the U.S., where screening is widely used, researchers reported it did not save lives in a study of 76,000 men. In Europe, where the practice isn't routine, a study of 162,000 found a modest reduction - about 7 fewer deaths per 10,000 men screened. But that screening put more men at risk of getting treatments they didn't need.

The studies are continuing and may eventually provide more definitive answers, researchers said.

Dr. Alan Wein, chairman of urology at the University of Pennsylvania, says, "PSA screening for prostate cancer is not perfect -- but right now there doesn't seem to be anything to replace it that is agreed upon as a better test." Wein says right now, no test can predict what types of tumors are apt to grow over time and require treatment with surgery, radiation or drugs.

Wein urges patients considering a PSA test to discuss their feelings about how aggressive they would like to be if they were to be diagnosed with prostate cancer.

"Do they want to know if they have it, and would they want to be treated if they knew they had the disease? If the answer to that is no, then there isn't any sense to screening," he says.

The studies were released Wednesday by the New England Journal of Medicine in connection with a conference in Sweden.

Dr. Leonard Gomella, the chairman of urology at Jefferson University Hospital says one of the studies released is still in progress, so it's much too early to know whether it's results are conclusive.

He told Action News, "Studies such as these send a mixed message to patients. Some may say "do not worry about prostate cancer," but the fact is that this is the leading solid tumor in men and the second leading cancer killer, facts that are difficult to ignore."

Dr. Gomella says the approach to many tumors need not be as aggressive as previously thought.

"For example, the concept known as "watchful waiting" or "active surveillance" where the patient is followed and treated only if the cancer begins to become a risk is becoming more accepted."

Prostate cancer is the most common cancer in men in the U.S. and Europe. More than 186,000 cases will be diagnosed this year in American men and 28,660 will die of the disease.

Screening is done with a blood test that measures prostate specific antigen, or PSA. Levels of PSA can be high for many reasons and a biopsy is needed to confirm a tumor. Many tumors grow so slowly that they won't be a threat, but there's no sure way to tell which are the dangerous ones.

And there's no agreement on the best treatment approach - "watchful waiting," surgery, hormone therapy or radiation. The treatments can lead to impotence and incontinence.

No major medical group recommends routine screening because there's no proof that it actually saves lives. That's the question the teams of researchers took on when the studies began in the 1990s.

Both groups are reporting their results a few years early. In the U.S., a panel monitoring the research decided there was enough evidence so far that screening wasn't saving lives and may have been leading to unnecessary treatment with serious side effects.

That study involved 76,693 men ages 55 to 74 from 10 cities. They were assigned to get six annual PSA tests and four digital rectal exams or regular care from their doctors, which could include screening. About half of the men getting usual care ended up getting screened at some point.

After seven to 10 years of follow-up, more cases of prostate cancer were found in the group that got annual screening, but no difference between the groups in the number of cancer deaths. The researchers plan to follow all the men for at least 13 years.

The U.S. researchers cautioned against comparing their results to the European research. Differences in how the studies were done and improvements in treatment may have contributed to the different results, they said.

The European results were based on 162,243 men between 55 and 69 in seven countries. Generally, the men were offered screening every four years or they got none. On average, they were followed for about nine years.

They found that screening lowered the rate of death by 20 percent.

Dr. Fritz Schroder, lead author of the study from the Netherlands' Erasmus Medical Center in Rotterdam, said he believes that the study will show even more lives saved as the men are followed years longer.

The European researchers noted a high risk of overdiagnosis - the finding and treating of cancers that wouldn't threaten lives. They said 48 additional men would need to be treated to prevent one death from prostate cancer.

"My interpretation of the two studies together is that PSA screening likely does save some lives but does significant more harm," said Dr. Otis Brawley, the American Cancer Society's chief medical officer.

The researchers and others agreed the results bolster advice that screening shouldn't be done in those with a limited life-expectancy. U.S. guidelines issued last year said men over 75 shouldn't be screened; no recommendation was made for younger men but they were advised to discuss the test with their doctor.

What's needed, the researchers said, is a better way to tell which prostate cancers need to be treated.

"When we find prostate cancer, we don't know if it is a killer cancer or what has been termed a toothless lion - the kind of cancer that men will die with, not of," said the U.S. study's leader, Dr. Gerald Andriole of Washington University School of Medicine in St. Louis. He said the tendency is to treat all patients aggressively.

The U.S. study is part of a National Cancer Institute project; the European study was supported mostly by government and health agencies. Some of the researchers report receiving grants and fees from drugmakers; one holds a patent for a PSA test.

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