Prostate-specific antigen(PSA) in serum exists in several molecular forms that can be measured by immunodetectable assays; free PSA, PSA complexed to α1-antichymotripsin and total PSA, which represents the sum of the free and complexed forms. We
have
determined the amount and ratio of these forms may be useful for increasing the ability of PSA to be used in distinguishing prostate cancer(PCa) from benign prostatic hyperplasia(BPH).
We evaluated 117 asymptomatic healthy male controls(mean age 55.8, range 50-71) with no clinical evidence of PCa, 125 men with symptomatic BPH(mean age 67.6, range 52-89) who underwent prostatic surgery(open prostatectomy or TURP) and 14 men with
biopsy-proven, untreated PCa(mean age 71.3 range 54-86). Using ACS-PSA2 assay(Ciba-Corning), we measured the free PSA(F), total PSA(T) and free/total(F/T) ratio, The method utilized was monoclonal-polyclonal immunometric, chemiluminescent assay,
using a
standardized calibratory 90:10. We also performed total PSA measurement with Tandem-r PSA assay(Hybritech).
Correlation between ACS-PSA2 assay and Tandem-R PSA assay was exfellent (r2=0.93). Receiver operating characteristics(ROC) analyses between them showed very similar performances. ROC analysis of free to total PSA ratio was more superior than that
of
free form PSA only. When all subjects were included, the ratio of free to total PSA in controls, BPH and PCa were 0.27, 0.24 and 0.07, redpectively, which sinificanlty differentiated between PCa and benign conditions(p<0.01). When the cut-off
value
(F/T) was set into 0.12, its diagnostic senitivity and speciticity were 86% and 84%, respectrively.
These findings suggest that free to total PSA ratio may enhance the ability to distinguish benign histologich conditions from cancer.
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