Jan. 9, 2006 -- Does PSA screening for prostate cancer reduce risk of death? New research suggests the answer is no, but the truth may not be known for several years, one expert says.
A study from the Yale School of Medicine and the VA Connecticut Healthcare System found no evidence that PSA screening improved survival in men with prostate cancer.
Researchers concluded that men should not be told that annual PSA screening can reduce their risk of dying from the cancer.
"Unfortunately, screening tests can sometimes find cancer, even at early stages, but not prolong survival," says researcher John Concato, MD, MPH.
"Rather than encouraging annual screening of all men starting at age 50, as is commonly done, the limited effectiveness of PSA testing should be explained to patients in the process of obtaining their informed consent to the test."
Test's Value Unclear
More than 230,000 American men were diagnosed with prostate cancer in 2005, and while one in six men will have prostate cancer in a lifetime, one in 34 will die from it, according to figures from the American Cancer Society.
The problem? Low PSA levels don't necessarily mean a man doesn't have the disease, and high levels don't necessarily mean that prostate cancer will progress and become life-threatening.
The American Cancer Society urges doctors to offer PSA screening and digital rectal exams to men beginning at age 50. Men at high risk, including black men, should begin testing at age 45, according to the ACS.
But the group does not recommend routine testing, and it calls on doctors to inform their patients about the "benefits and risks of testing at annual checkups."
The ACS guidelines on PSA testing state that patients "should actively participate in the decision by learning about prostate cancer and the pros and cons of early detection and treatment of prostate cancer."
Likewise, the U.S. Preventive Services Task Force says the evidence isn't strong enough to recommend routine PSA testing, and the American College of Physicians also calls on its members to explain the pros and cons of the test to their patients.
The ambiguity stems from the fact that the research on the value of PSA in prostate cancer has been mixed.
In a study reported last July, researchers in Canada found that screening reduced the risk of developing advanced disease by 35%.
The latest study, published today in the Archives of Internal Medicine, followed a similar design but used long-term survival as its endpoint.
No Survival Advantage Seen
From approximately 72,000 veterans receiving care at 10 VA medical centers in New England, Concato and colleagues identified 501 men aged 50 and older who were diagnosed with prostate cancer between 1991 and 1995 and had died of the disease by 1999. An equal number of living VA patients, matched for age and place of treatment, were included in the study as a comparison group.
The researchers found that 14% of the men who died of prostate cancer and 13% of those who did not die had been screened using the PSA test. The overall risk for death after adjusting for race and coexisting medical conditions showed no increased risk.
"If screening worked, men who died would have had less testing than those who lived," says Concato.
The Yale University professor of medicine suggests that men with strong fears of prostate cancer and those who fully understand the potential risks associated with treatment may still want to have routine PSA testing.
Informed men who feel the potential risks outweigh the benefits should not be pressured into having the test, he says.
"Doctors should mention that the PSA test isn't perfect and that screening may lead to possible harm as well as potential benefit," he says. "The benefits include the potential for improved survival in some men. The harms include possible treatment-related side effects, including incontinence and impotence, for therapies that may be unnecessary (for slow growing tumors) or ineffective (for aggressive ones)."
In an editorial accompanying the study, Michael J. Barry, MD, of Massachusetts General Hospital, wrote that it remains to be seen if PSA testing results in improved prostate cancer survival.
Two large clinical trials under way in the United States and in Europe should provide more definitive answers, he says. The results of these studies should give more information about the effectiveness of prostate cancer screening. Results from the trials are expected sometime in 2009.
"I have been writing that we need to wait for trials to see if prostate cancer screening does more good than harm for so long, sometimes I despair of ever knowing the answer," he writes, adding that "help is now not that far away."