-Abstract-
Purpose : To maximize the clinical use of percent free PSA measurement, it is essential to understand
what factors other than prostate cancer influence percent free PSA. We evaluated the effect of prostate
volume, age, total PSA level and histological evidence of inflammation in prostate needle biopsies on
percent free PSA in men without clinically detectable prostate caqncer.
Materials and Methods : Total and free PSA levels were determined using PSA-RIACT and
FPSA-RIACT kit (Cis Bio International, France). In 154 men with total serum PSA levels between 2.6
and 19.9ng/ml, who showed benign pathology, the correlation among age, prostate volume, total PSA and
percent free PSA was evaluated. Also we investigated the change of total and free PSA as a function of
age, prostate volume, and presence of prostate inflammation. Additionally, total men were stratified by 3
groups according to serum PSA level, we evaluated difference of mean value of percent free PSA.
Multivariate regression analysis was done to predict total PSA as a function of age prostate volume, and
to predict percent free PSA as a function of age, prostate volume and total PSA.
Results : Percent free PSA level was correlated with age (r=0.237, p<0.01) and prostate volume (r=0.323,
p<0.05) but mot with total PSA (r=-0.141, p=0.08). The mean percent free PSA was significantly
increased with increasing age and prostate volume and decreased with the presence of prostate
inflammation. When the patients were classified by total PSA, the statistically significant difference of
mean percent free PSA was not achieved. Using the multivariate regression analysis, age and prostate
volume did not have statistical significance to predict total PSA (R2=0.18, p=0.12), but age,
prostate volume and total PSA level had statistical significance to predict percent free PSA
(R2(/sup>=0.28, p=0.0001).
Conclusions : Among men without clinically detectable prostate cancer and with total PSA level between
2.6 and 19.9ng/ml, percent free PSA was higher in older age group, in large prostate group, and in men
without prostate inflammation but total serum PSA level did not influence to the percent free PSA
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