The utility of PSA density and free PSA in the prostate biopsy decision-making process in a South African population.

Abstract

Background: Controversy around the role of PSA screening for prostate cancer still exists because evidence has not yet shown that it saves lives. Additional tests used in conjunction with PSA, can improve the sensitivity and specificity after screening when deciding which patients should be biopsied (-during screening), thus potentially reducing the number of unnecessary prostate biopsies and reducing the number of clinically insignificant prostate cancers that are detected. Methods: A retrospective chart review was undertaken on a heterogeneous group of South African men from a private urology practice in Johannesburg, South Africa. PSA, prostate volume, PSA density (PSAD), free PSA (fPSA) and prostate histopathological diagnosis were assessed. Results: Of the 227 patients included, 59.9% were diagnosed with prostate cancer and 40.1% with benign pathology. The mean age was 60.5 years. The mean PSA (p<0.001), fPSA (p=0.043) and PSAD (p<0.001) were significantly different between the cancer and the benign groups. The area under the ROC curve for PSA was 0.83 (p<0.001) with an ideal cutoff of greater than 4.87ng/mL to detect cancer, for fPSA was 0.66 (p=0.036) with a cutoff of <12.25% and for PSAD was 0.86 (p<0.001) with a cutoff of > 0.11 ng/mL/cm3. In the prostate biopsy decision-making process, using a PSAD > 0.1ng/mL/cm3 or a percentage fPSA <= 12% in addition to the standard indication of PSA >= 4ng/mL as an indication for biopsy would have prevented 21.1% of biopsies and 16.7% of clinically insignificant prostate cancer diagnoses but would have missed 8.6% of clinically significant cancers. There is a trend toward increasing PSA and PSAD and decreasing fPSA with increasing Gleason score. Conclusions: If PSA screening for prostate cancer is undertaken, the addition of PSAD and fPSA, both of which can be obtained in resource-constrained state hospitals, can reduce the number of clinically insignificant prostate cancer detected and the number of unnecessary prostate biopsies. This, however, runs the risk of a small reduction in the detection of clinically significant prostate cancer. Further investigation is required to minimise this risk. Patients with equivocal PSA values, but with PSAD > 0.1ng/mL/cm3 or fPSA <= 12% should be referred for further assessment.