Prostate Cancer Screening May Not Significantly Reduce Deaths, Two Studies Find
Thursday, March 19, 2009
Men are being urged to carefully consider risks before undergoing prostate cancer screening in the wake of two large, long-awaited studies that did not produce convincing evidence that routine testing significantly reduces the chance of dying from the disease.
The PSA blood test, which millions of men undergo each year, did not lower the death toll from the disease in the first decade of a U.S. government-funded study involving more than 76,000 men, researchers reported yesterday. The second study, released simultaneously, was a European trial involving more than 162,000 men that did find fewer deaths among those tested. But the reduction was relatively modest and the study showed that the tests resulted in a large number of men undergoing needless, often harmful treatment.
Together, the studies -- released early by the New England Journal of Medicine to coincide with presentations at a scientific meeting in Stockholm -- cast new doubt on the utility of one of the most widely used tests for one of the most common cancers.
"Americans have been getting screened for prostate cancer because there is this religious faith that finding it early and cutting it out saves lives," said Otis W. Brawley of the American Cancer Society. "We've been doing faith-based screening instead of evidence-based screening. These findings should make people realize that it's a legitimate question about whether we should be screening for prostate cancer."
Other experts were more circumspect, arguing that the European study did indicate at least some benefit for some men, and that the U.S. trial could eventually confirm those findings as it follows the men for longer periods. But they agreed that the new findings should prompt patients and their doctors to discuss the risks and benefits of the testing.
"It shouldn't be a knee-jerk response to get tested," said Christine D. Berg of the National Cancer Institute, which sponsored the U.S. study. "We should be telling these guys to go talk to their physician and say, 'In light of the current evidence and what you know about me and my health, what should I do?' "
Some researchers, however, remain supportive of routine testing, saying the U.S. study has flaws that could have limited its ability to detect a reduction in deaths.
"I don't think that screening should be summarily dismissed based on these trials," said E. David Crawford, a urology professor at the University of Colorado at Denver who helped conduct the U.S. study and heads the Prostate Conditions Education Council, which promotes testing. "I think they say we should be more smart when we screen."
The findings address perhaps the most important and contentious issue in men's health: how best to detect and treat prostate cancer. The disease is diagnosed in more than 218,000 U.S. men each year and about 28,000 die of it, making it the most common cancer after skin cancer and the second-leading cancer killer among men.
The PSA test, which measures a protein produced by prostate tissue called the prostate-specific antigen, has significantly increased the number of prostate cancer cases being caught at early stages. But it has been far from clear whether that translates into a reduction in deaths from the disease. Prostate cancer often grows so slowly that many men die from something else without ever knowing they had it.
Because it is not clear precisely what PSA level signals the presence of cancer, many men experience stressful false alarms that lead to surgical biopsies, which can be painful and in rare cases can cause serious complications.
Even when the test detects a real cancer, doctors are uncertain what, if anything, men should do about it. Many are simply monitored. Many others, however, undergo surgery, radiation and hormone treatment, which often leave them incontinent, impotent and experiencing other sometimes debilitating or even possibly life-threatening complications.