Producers Resource Center

PSA Test Unreliable Prostate Cancer Screening

New research reveals the prostate specific antigen (PSA) test may lead to overdiagnosis and overtreatment of prostate cancer.

Researchers noted that the inability of the PSA test to distinguish between deadly and harmless prostate cancers makes it unusable as a population-wide screening tool.  PSA is a protein made by the prostate gland. It is found in small amounts in the blood of healthy men, and is often elevated in men with prostate cancer, but also in men with benign prostate enlargement.

Some 745,000 men in the United States will be diagnosed with cancer this year according to the American Association for Critical Illness Insurance, the industry trade group.  Nearly 300,000 will die and prostate cancer causes about a quarter of all cancer deaths among men.

The lead author of one study, a urologist with Gavle Hospital in Gavle, Sweden, noted that in addition to PSA, further biomarkers are needed before inferring population-based screening for prostate cancer.  The claim was based on a study of PSA tests of over 500 men diagnosed with prostate cancer. Their PSA was measured several years before being diagnosed. Scientists compared those tests with PSA tests from over 1,000 men without prostate cancer.

Reserachers reported that in men with a prediagnostic PSA level below 1 nanogram per milliliter, only six men [1.2 percent] were later diagnosed with a high-risk prostate cancer. Hence, PSA levels below [that] almost ruled out a future high-risk prostate cancer diagnosis.  They noted that the direct implication of their findings in a screening situation was that no matter which PSA cut-off you adopt for selecting men for further diagnostic work-up, you will either have too many false positives or too many false negatives.

Given the current trend in lowering the PSA cut-off to about 3 nanograms per milliliter, the medical reserachers noted that a large number of healthy men will be subject to painful, stressful and costly diagnostic procedures.  Their report worried that the wide overdiagnosis of slow-growing tumors causing unnecessary medical treatment and anxiety.

Although most agencies providing recommendations on prostate cancer screening, especially those outside the United States, do not recommend routine PSA testing for the early detection of prostate cancer, it continues to be performed frequently medical experts noted.

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