Prostate cancer screening still unproven: report
Friday, July 3, 2009
NEW YORK (Reuters Health) – PSA blood tests are often used to screen men for prostate cancer, but there is still no good evidence that they cut death rates from the disease, a new review finds.
Based on two recent major clinical trials, the practice of routinely screening men with the PSA test has "at best" a small effect on deaths from prostate cancer, according to the review, published in CA: A Cancer Journal for Clinicians.
The studies, which came out earlier this year in The New England Journal of Medicine, appear to bolster the positions of the American Cancer Society (ACS) and other major medical groups, which do not recommend routine PSA screening for symptom-free men at average risk of developing prostate cancer.
PSA, or prostate-specific antigen, is a protein produced by the prostate gland, blood levels of which generally rise when a prostate tumor is present. PSA blood tests can catch the cancer in its early stages.
But while use of the test has led to more prostate cancer diagnoses, it has done little to nothing to actually cut death rates from the disease, according to the researchers on the new review, led by Dr. Otis W. Brawley of the ACS.
In one of the recent trials, U.S. researchers found that among more than 38,000 men between the ages of 55 and 70, annual PSA screening was no more effective than less-frequent screening at cutting prostate cancer death rates.
The second study, of 182,000 European men, found that PSA screening every few years was associated with only a modest reduction in death risk.
The central problem with prostate cancer screening is that most prostate tumors are slow-growing and would not be deadly even without treatment. So screening can lead to unnecessary treatment of cancers that would never had been life-threatening.
Because prostate cancer treatments, such as surgery and radiation, can have side effects — incontinence and erectile dysfunction, for instance — it is possible to do many men more harm than good by treating small tumors.
Researchers are continuing to study ways to refine prostate cancer screening, Brawley and his colleagues point out. That includes measuring "biomarkers" other than PSA that may be able to not only signal the presence of tumors, but also indicate whether they are aggressive and require immediate treatment.
Until then, the researchers say, men should talk with their doctors about whether PSA screening is a good idea. A man’s personal risk factors for the disease — including his family history of prostate cancer — are key in that decision, according to Brawley’s team.
The ACS recommends that most men discuss the possibility of PSA screening with their doctors starting at age 50. Men who are at relatively higher risk — including those with a brother or father who developed prostate cancer before the age of 65 — can have that talk after age 40. PSA screening is not generally recommended for men age 75 and older.
SOURCE: CA: A Cancer Journal for Clinicians, July/August 2009.
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