Just Say No to the PSA Prostate Cancer Test
Posted by medconsumers on April 16, 2009
“Studies Fail to Settle Prostate Screening Debate” (Boston Globe);
“Prostate Screening Saves Lives” (BBC).
“Prostate Cancer Screening May Not Reduce Deaths” (Washington Post).
These are just some of the headlines for the big health story last month about the PSA (prostate-specific antigen) screening blood test. The results from two long awaited clinical trials were released early and simultaneously by The New England Journal of Medicine on March 18. Despite the seemingly conflicting messages of these sample headlines, it is now clear that symptomless men should consider refusing this test.
The larger of the two trials was conducted in several European countries. It found that the lifesaving benefit of PSA screening is far more modest than previously thought…and the risk of harm is very high. For every 1,400 men who regularly had a PSA screening test over the ten-year period of the European trial, one man avoided death from prostate cancer and 47 men were treated unnecessarily for a cancer that did not progress. The risks of treatment include urinary incontinence, bowel problems, and impotence. Otis W. Brawley, MD, chief medical officer of the American Cancer Society, summed up the findings this way: “The test is about 50 times more likely to ruin your life than it is to save your life.” (Click here for Treatment for Early Prostate Cancer.)
The other trial was U.S. government-funded and, unlike the European trial, it showed no reduction in prostate cancer deaths. The predictable and disturbing finding from both trials is this—many more prostate cancers were diagnosed in the men who were screened with the PSA test than in those who were not. Few men opt for the “wait and see” approach once a PSA test, biopsy and other tests indicate the presence of cancer.
The debate over the PSA test is expected to continue, largely because flaws can be found in virtually all trials. For example, the U.S. trial had less than half the number of participants of the European trial (162,000), which some believe may account for the absence of a lifesaving benefit. In the U.S. trial, men were randomly assigned to annual PSA tests plus a digital rectal examination (screened group) OR what is known as usual care.
Given the fact that the PSA test has been aggressively marketed as a lifesaving test to doctors and the general public for the last 20 years, usual care in the U.S. involves a doctor recommending a PSA test. It is considered unethical to ask men in the unscreened control group not to have a PSA, and a large portion of them in the U.S. trial—38% to 52%—had the test. Western European countries put up barriers to the marketing of an unproven test to the public. In the U.S., most men over age 50 have regular PSA tests; in the U.K., where the National Health Service does not recommend PSA testing, only about 6% of men have had a PSA test because they requested one.
There was a troubling finding from the U.S. trial that did not get media attention last month—it involves the deaths from the prostate cancer treatment itself. When the authors of this trial looked solely at the participants who had been diagnosed with prostate cancer in the 10-year period of the trial, there were 312 men in the PSA screening group and 225 men in the unscreened control group who had died from causes other than prostate cancer. The unexpectedly higher number of deaths in the screened group, say the authors, is “possibly” related to treatment of non-progressive cancer.
The question that no one seems to be asking at this time is: Why was the PSA screening test allowed to become so widespread when it cannot identify which prostate cancers are aggressive and lethal? And no test currently exists that can make that distinction accurately.
Cancer screening tests are approved by the FDA on the basis of an outdated understanding of cancer, i.e. all cancers are deadly; finding cancer early is always good.; treatments are more effective with early diagnosis. All a company has to do is prove its product can find symptomless cancers. The success of any screening test, however, should based on how many deaths can be avoided. And most important, the chance of avoiding death should be far greater than the chance of serious harm as a result of the test itself. The PSA screening test fails on both counts.
What to do:
- Inform yourself. Try to get as much information about prostate cancer, early detection, and the PSA test from sources other than hospitals and doctors who treat prostate cancer. The National Cancer Institute is one place to start (www.cancer.gov).
- Be aware of the fact that some men are given the PSA test without their knowledge. It is often automatically added in with the standard blood test for cholesterol, etc. If you decide to forego a PSA test, make your wishes known before you are given a blood test.
- Recognize that fear-mongering with statistics is essential to cancer screening promotion. Prostate cancer may in fact be the second leading cause of cancer death in men, but it accounts for only 3% of all deaths. No prostate screening campaign is likely to flip that statistic around to tell men that 97% of them will not die of prostate cancer. And the 20% reduction in prostate cancer deaths shown in the PSA screened group in the European study. Here’s what it means: The man who regularly has a PSA test over the course of the next ten years will reduce his risk of dying of prostate cancer from 3% to 2.4%.
Maryann Napoli, Center for Medical Consumers© April 2009