Study Knocks Diagnostic Value of Prostate Cancer Screening Test

Feb. 25, 2010— -- If prostate biopsies were based only on the rate of change in PSA level over time, the number of unnecessary biopsies would be almost four times the number of additional cancers diagnosed, data from a large clinical trial showed.

In the absence of other predictive factors, so-called PSA 'velocity' would have identified 115 prostate cancers at a cost of 433 unnecessary biopsies, according to Andrew Vickers of Memorial Sloan-Kettering Cancer Center in New York City and colleagues.

If used as sole justification for a biopsy, PSA velocity would trigger about one of every seven prostate biopsies, they reported online in the Journal of the National Cancer Institute.

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Moreover, adding PSA velocity to a multifactor model resulted in minuscule improvement in diagnostic accuracy, particularly for high-grade cancers.

The findings have implications for clinical guidelines that include PSA velocity in criteria for prostate biopsy, including recommendations from the American Urological Association (AUA) and the National Comprehensive Cancer Network (NCCN).

"We found no reason to believe that implementation of the guideline would improve patient outcomes; indeed, its use would lead to a large number of unnecessary biopsies," Vickers and co-authors wrote in conclusion. "We therefore recommend that organizations issuing policy statements related to PSA and prostate cancer detection remove references to PSA velocity."

The authors did acknowledge that current clinical guidelines for prostate cancer have a strong evidentiary base for many aspects of diagnosis, evaluation, and treatment; in particular, use of PSA and free PSA levels to diagnose cancer.

However, they noted, inclusion of PSA velocity in clinical recommendations has questionable support.