Tuesday, May 22, 2007

PSA Test Still Important to Detect Prostate Cancer, Studies Find

(HealthDay News) -- Despite questions as to whether early screening for prostate cancer is accurate, new research suggests it continues to be important.

And even more encouraging news indicates that statins, drugs designed to lower cholesterol, might also reduce the risk of developing prostate cancer. Both sets of findings were presented Sunday at the American Urological Association's annual meeting, in Anaheim, Calif.

Screening for prostate cancer has become controversial, particularly the issue of whether a prostate-specific antigen (PSA) blood test is useful as an early detector of malignancy. Two studies presented at the conference indicate it is still worthwhile to have such a test.

In one study, Dr. Hans Lilja, from Memorial Sloan-Kettering Cancer Center in New York City, and colleagues found that PSA testing of men in their 40s was predictive of developing prostate cancer later. In fact, the higher the initial PSA, the greater was the probability that the cancer would be aggressive, the research showed.

As recently as last month, a study published in the Journal of the National Cancer Institute found that PSA tests "perform poorly in distinguishing between those who develop a lethal prostate cancer from those at low or no risk of disease progression."

But among the patients in the Sloan-Kettering study, risk for prostate cancer was concentrated, with 89 percent of advanced cancers occurring in men with the top 10 percent of PSA levels, the researchers found.

Lilij thinks that men should have an initial PSA test when they are in their 40s rather than waiting. "It is surprising that this marker can predict cancer 20 years later," he said. "We should focus our efforts on those men who are on the highest risk for cancer."

Another study found that among patients who had a radical prostatectomy (removal of the prostate and some of the tissue surrounding it), those who had been screened for prostate cancer were more likely to have malignancy confined to the prostate, compared with men who had not been screened.

"Patients should be screened," said lead researcher Dr. Alexandre E. Pelzer, from the Medical University Innsbruck, Austria. "Screening reduces mortality from prostate cancer by 50 percent in our part of Austria, where screening is done, compared with other parts of the country where it isn't," he said.

Another debate in prostate cancer care is whether patients diagnosed with the disease should be treated immediately or whether watchful waiting is best.

In one study, Dr. Marc A. Dall'Era, and colleagues from the University of California, San Francisco, found that it was not possible to predict how fast the cancer would progress among the study subjects who had what was termed low-risk prostate cancer.

In the study, more than 400 men had their cancer watched monthly. "Among the men on active surveillance, about 28 percent progressed," Dall'Era said. "Over five years, none of the men died from prostate cancer," he added.

Men who opted for treatment were those who had the highest grade tumors, Dall'Era added.
In another study, Dr. Bradley A. Erickson, from Northwestern University, and colleagues collected data on 347 older men who selected watchful waiting. Among these men, 36 percent showed progression and/or underwent secondary treatment. Overall mortality was 30 percent, with 8 percent dying from prostate cancer.

"Men who were more likely to die were those with higher PSA and those whose cancer progressed," Erickson said. "This is the first study to that gives us a natural history of PSA screening."

In a second group of studies, researchers presented evidence that statins might reduce prostate cancer risk.

In the first report, Dr. Janet Colli, and colleagues from the University of Alabama, Birmingham, were able to make an association between declining prostate cancer rates in the United States and statin use.

The researchers said they found the declining death rates were most noticeable among white men who used statins. "There was a very strong correlation between declining prostate cancer mortality rates and declining high cholesterol levels in white males," Colli said.

Colli thinks statin use may be one reason for this decline in prostate cancer mortality. "Future studies are needed to determine the effect of statins on prostate cancer," she said.

In a second study, a research team led by Dr. Robert J. Hamilton, from Duke University Medical Center, found statins lower PSA levels. "In 1,200 men, we found an average 4.1 percent decline in PSA after starting their statin," Hamilton said. "The PSA dropped more if the patient was on a higher dose of a statin."

Moreover, men whose PSA was highest saw the greatest drop in PSA levels after starting statins, Hamilton said. "These men had an average of a 15 percent drop in their PSA," he noted.
Hamilton said studies need to be done to see if statins actually protect against prostate cancer.

He added the concern that statins may not prevent cancer, but rather mask the malignancy through the decline in PSA levels, so some prostate cancers may go undiagnosed.

In a third study, a group headed by Dr. Teemu J. Murtola from the University of Tampere, Finland, collected data on 78,484 Finnish men between the ages of 55 and 67.

They found that there were fewer cases of prostate cancer among men who used statins. "There was a dose-dependent reduction in prostate cancer among users of statins, but not among users of other cholesterol drugs," Murtola said. "The overall risk of prostate cancer was around half of that of non-statin users."

In addition, Murtola's team found that PSA levels were also lower among study subjects without cancer who used statins.

"The association of statins with the reduced risk of prostate cancer should be made known to men taking statins," Murtola said.

More information
For more information on prostate cancer, visit the U.S. National Cancer Institute.

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