THURSDAY, March 19, 2009 (HealthDay News) -- In the wake of yesterday's publication of two major studies on the prostate-specific antigen (PSA) test to detect prostate cancer -- one finding that it didn't save lives and another finding that it did -- American men may be wondering if the test is still worth taking.
The studies, published in the New England Journal of Medicine, probably won't end the long controversy surrounding a blood test that millions of men have routinely been taking for years.
While an elevated PSA reading may indicate a life-threatening cancer, it may also detect much slower moving tumors that would never cause death. Because doctors cannot yet tell the difference, treatments are often ordered that can impair men's quality of life -- causing many experts to worry that the PSA test is overused.
The American Cancer Society, for one, does not currently recommend routine PSA screening for all men.
"We stopped mentioning screening in 1997, and since then have been for 'informed decision-making,'" said Dr. Otis Brawley, chief medical officer of the society. "We recommend that the physician should offer the test and inform men of the potential risk and potential benefit of screening."
One of the NEJM studies, which followed almost 80,000 American men for seven years, found no reduction in prostate cancer deaths among those who had regular PSA tests, compared to men who made no special attempt to have such tests. But the other study, which included 182,000 European men, found a 20 percent lowering of prostate cancer deaths among men who had such screening.
"At least initially, these won't change our recommendations," said the ACS' Brawley. However, "we will get our prostate cancer advisory committee together to consider the issue," he added.
According to Brawley, men at higher risk of prostate cancer, such as those with a family history and African-Americans, should have that conversation with a physician at age 45, while most men can wait until age 50.
African-American men have a higher incidence of prostate cancer and a higher risk of dying of the malignancy.
But Dr. Judd Moul, director of the Duke University Prostate Center, sees flaws in the U.S. study (which argued against a mortality benefit) that he believes invalidate its findings.
"In the American study, the control group was under routine medical care, and in that control group, half the men had PSA screening," Moul said. "So, it was screening versus 'semi'-screening."
In addition, there was no provision in the American study that men with high PSA levels should seek treatment, Moul said. "It's not a screening test if it isn't followed up with treatment," he said.
Moul has an admittedly personal interest in the subject, since his father-in-law died of prostate cancer. And, he said, he has vivid memories of the pre-PSA-test era, when most men with the disease were only diagnosed at an advanced, tough-to-treat stage.
"I don't want to go back to the days when I had patients all over the ward dying of painful metastatic prostate cancer," Moul said.
And so, he prefers the recommendation of the National Comprehensive Cancer Network, formed by major U.S. cancer centers, that all men have an initial PSA test at age 40, which would indicate their risk of developing prostate cancer, with follow-up testing at age 45. "After age 50, I would follow the recommendation of the American Cancer Society," Moul said.
And PSA testing should certainly stop at age 70, said Dr. Derek Raghavan, chairman of the Cleveland Clinic's Taussig Cancer Institute -- but with one caveat. If previous annual tests have shown a rising level of PSA, a protein produced by the prostate, testing should continue, Raghavan said.
"The studies certainly have added fuel to the controversy about PSA testing," Raghavan said. It is a controversy that starts with the knowledge that a PSA test is not cancer-specific. A high reading must be followed by a biopsy to find if cancer is present.
A finding of cancer also opens the door to a second level of controversy, because prostate tumors are notoriously variable. Some can grow aggressively and fatally. Many grow so slowly that they are no danger to life. But no test currently available can tell the difference between a life-threatening and an indolent prostate cancer.
On the other hand, aggressive treatment of prostate cancer carries its own dangers, which include possible incontinence and impotence. Raghavan noted that the overall survival in the European trial was the same for those who had screening and those who did not, while Brawley was uncomfortable with the European finding that 48 men had to be treated to save one life.
"The data that have come out show only a small relative benefit," Raghavan said. "For people who are looking for an argument for screening, it isn't there."
Moul countered that, "we may be detecting many cancers that never threaten lives. But we are saving lives."
More information
There's more on prostate cancer at the U.S. National Cancer Institute.
