Free and Total Prostate Specific Antigen in Benign Prostate Hyperplasia and Prostate Cancer
J Coll Physicians Surg Pak, Vol. 14, No. 2, pp. 69-71, February 2004
Posted: 25 May 2011
Date Written: 2004
OBJECTIVE: To record the levels of PSA in the sera of prostate cancer (CaP) and benign prostatic hyperplasia (BPH) cases. Free PSA/total PSA as percentage was also calculated in order to evaluate its utility in differentially diagnosing BPH and CaP.
DESIGN: A cross-sectional, case control study.
PLACE AND DURATION OF STUDY: Shaikh Zayed Hospital and Mayo Hospital, Lahore from August 2002 to March 2003. Materials and Methods: A group of 108 male subjects, including one-third of each of biopsy-confirmed prostate cancer cases, BPH cases and asymptomatic controls of matching age were studied. PSA and Free PSA were determined by ELISA using commercially available assay kits.
RESULTS: Mean PSA was found to be highest in CaP cases (41.9 /- 38.7 ng/ml), lower in the BPH cases (13.5 /- 10.5 ng/ml), while it was lowest in the control subjects (5.7 /- 4.4 ng/ml). Moreover, it was observed that a majority of the CaP cases had serum PSA >20 ng/ml, 50% of BPH cases had serum PSA in the 'gray zone' (4.1-20 ng/ml), while majority of controls had serum PSA in the 'normal' range (0 - 4 ng/ml). Using a free- PSA "cut-off" of 18% to differentiate between benign and malignant prostate enlargement, it was found that 80% of the CaP cases had F/T% <18, while 75% of the BPH cases had F/T%>18. The percent free-PSA test to differentially diagnose BPH and CaP in the 'gray zone' was found to have a sensitivity of 86% and a specificity of 94%.
CONCLUSION: Using a cutoff of 18%, the free-PSA test significantly improved the differential diagnosis of BPH and CaP in the 'gray zone' as compared to the use of total PSA alone in the study group.
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