Screening men for prostate-specific antigen
(PSA), the most commonly used tool for detecting prostate cancer
, has become a ‘hugely expensive public health disaster,’ says the researcher who discovered PSA in 1970.
Richard Ablin, PhD, research professor of immunobiology and pathology at the University of Arizona College of Medicine in Tucson, expressed his forthright views in an opinion piece entitled The Great Prostate Mistake, which was published in the New York Times on March 9. Dr. Ablin says: ‘The test is hardly more effective than a coin toss,’ in detecting prostate cancer. He also writes: ‘As I've been trying to make clear for years now, PSA testing can‘t detect prostate cancer.’ He points out that infections, over-the-counter drugs like ibuprofen, and benign swelling of the prostate can all elevate PSA levels.
More important, the test cannot differentiate between prostate cancer that is rapidly growing and potentially fatal from one that is growing slowly and will not kill, he adds. PSA testing does have a role, he says. One example is the use of the test to follow patients who have had treatment for prostate cancer, where a rapidly rising score indicates a return of the disease.
There are already some signs of changing attitudes. Two huge studies published last year showed that PSA screening had either no or little effect on the death rate from prostate cancer (New Engl J Med. 2009;360:1310-1319 and 1320-1328). These and other data have led to the realisation that many men diagnosed with PSA screening are being overtreated.
The medical community is ‘slowly turning against PSA testing,’ Dr. Ablin writes. As evidence, he cites the new update to American Cancer Society guidelines published last month, which ‘urged more caution in using the test.’ In addition, the American College of Preventive Medicine has concluded that there is ‘insufficient evidence to recommend routine screening,’ he notes.
However, the American Urological Association (AUA) still recommends screening — ‘shamefully,’ according to Dr. Ablin. The US National Cancer Institute is ‘vague on the issue, stating that the evidence is unclear.’ The US Preventive Services Task Force recently recommended against PSA screening for men who are 75 year or older, but this group has still not made a recommendation either way for younger men, he notes. In Australia, the Australian and New Zealand Urological Society recommend screening and in a press release dated September 23, 2009 recommended reducing the age for first PSA screening in men from 50 to 40 years. However the Cancer Council of Australia and Andrology Australia both recommend against general screening using PSA.
The problem with screening for prostate cancer using PSA is that many of the men with elevated PSA will not have cancer and many of the men who do have an elevated PSA and prostate cancer would have been better off if the test were never done as they will die of something else before their prostate cancer ever gives them any problems. Treatment of early prostate cancer is reasonably effective but in many cases it comes with a cost in the form of urinary incontinence, impotence and other side-effects. Prostate cancer screening in men differs from breast and cervical cancer in women and colorectal cancer screening in both sexes because a large proportion of prostate cancers are very slow-growing and thus do not need to be treated. The PSA test does not distinguish between these cancers that can be ignored and the cancers that will progress and eventually kill the affected men.