The utility of PSA density and free PSA in the prostate biopsy decision pathway in a South African population

Abstract

Background: Controversy around prostate-specific antigen (PSA) screening for prostate cancer exists because evidence has not shown that it saves lives. Simple additional tests can improve its sensitivity and specificity, reduce unnecessary prostate biopsies and reduce the diagnosis of clinically insignificant prostate cancer.

Methods: A retrospective chart review was undertaken on a heterogenous group of South African men. This review assessed PSA, prostate volume, PSA density (PSAD), free PSA (fPSA) and prostate histopathology.

Results: Of 227 men with a mean age of 60.5 years, 59.9% had prostate cancer, and 40.1% had benign pathology. The mean PSA (p < 0.001), fPSA (p = 0.043) and PSAD (p < 0.001) were significantly different between those participants with cancer and those without. The area under the receiver operating characteristic (ROC) curve for PSA was 0.83 (p < 0.001) with a cut-off of > 4.87 ng/ml to detect cancer, the area for fPSA was 0.66 (p = 0.036) with a cut-off of < 12.25% and the area for PSAD was 0.86 (p < 0.001) with a cut-off of > 0.11 ng/ml/cm³. In the prostate biopsy decision pathway, PSAD > 0.1 ng/ml/cm³ or fPSA < 12% in addition to PSA > 4 ng/ml as an indication for biopsy would have prevented 21.1% of biopsies and 16.7% of clinically insignificant prostate cancer diagnoses, but missed 8.6% of the clinically significant cancers. There is a trend toward an increasing PSA and PSAD and a decreasing fPSA with an increasing grade.

Conclusion: The use of PSAD and fPSA in the prostate biopsy decision pathway can reduce the detection of clinically insignificant prostate cancer and the number of unnecessary prostate biopsies, with an associated small reduction in the detection of clinically significant prostate cancer.