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Urology. 1999 Aug;54(2):220-4.

Use of percentage of free prostate-specific antigen to identify men at high risk of prostate cancer when PSA levels are 2.51 to 4 ng/mL and digital rectal examination is not suspicious for prostate cancer: an alternative model.

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Division of Urologic Surgery, Washington University School of Medicine, St. Louis, Missouri, USA.



Currently, many clinicians do not recommend prostate biopsy for men with digital rectal examination (DRE) results that are not suspicious for cancer and prostate-specific antigen (PSA) values between 2.51 and 4 ng/mL. We propose a new model for the detection of prostate cancer using the percentage of free PSA (%FPSA) in the limited range of PSA values between 2.51 and 4 ng/mL that maximizes clinical specificity (ie, minimizes false-positive results). This model identifies higher risk patients in this relatively low-risk population.


Three hundred sixty-eight archived serum samples from men evaluated and treated at two academic institutions were reviewed. All men had a histologic diagnosis, findings not suspicious for cancer on DRE, and PSA levels between 2.51 and 4 ng/mL. Samples were tested in Hybritech's Tandem-R PSA and Tandem-R free PSA (FPSA) assays in the same laboratory at each institution.


Various models for cancer detection using %FPSA when PSA is 2.51 to 4 ng/mL and DRE is not suspicious for cancer are proposed. These models recommend biopsy for only 10% to 36% of the men in this population and would identify as many as 30% to 54% of the detectable cancers. There is evidence that the cancers that would be detected are the most aggressive cancers in this population.


Our models identified men with a higher risk of prostate cancer in a relatively low-risk population that currently does not routinely undergo biopsy. This may allow for a more cost-effective way to increase cancer detection when PSA values are between 2.51 and 4 ng/mL and DRE is not suspicious for cancer. This model has the potential to detect a greater number of clinically important and potentially curable cancers than would be detected with current practice.

[Indexed for MEDLINE]

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