[Analysis of reference range responsible to normal percent value of free prostate specific antigen from men without...

To study the effect of age on the percent value for free prostate specific antigen (fPSA) from men, and the relationships between the percent fPSA and the pathological grade or the clinical stage of prostate cancer (PCa), and also to determine appropriate reference value range for Chinese men.

A total of 713 participants were enrolled into the study, with the serum PSA, fPSA measured and the percent fPSA calculated. Out of 713, 679 men without prostate disease were divided into 5 groups by age, and then the relationships were studied between man age and PSA, fPSA or percent fPSA, respectively. The relationships between pathological grade or clinical stage and percent fPSA were also studied in the rest 34 participants suffering from PCa. With the help of the related data of men without prostate disease, the appropriate reference value range was established for Chinese men.

PSA and fPSA were positive correlated with age (r was 0.608 and 0.534 respectively, P < 0.001), while there was no significant correlation between age and percent fPSA. The percent fPSA was also correlated with pathological grade, clinical stage of Pca (r was 0.427 and -0.332 respectively, P < 0.05). According to the data of our early studies and the reference value range of percent fPSA given by the test kit and the previously reported medical references, the data of 10%, 15% and 20% were selected as the percent fPSA threshold values to distinguish PCa or health men without prostate disease. The sensitivity of diagnosing PCa was 94.1% and the specificity was 89.7% when the reference range was more than 15%. When the reference range was more than 10%, the sensitivity of diagnosing PCa was 70.6% and the specificity was 97.4%. When the reference range was more than 20%, the sensitivity also was 94.1%, but the specificity merely was 62. 8%. The reference range of percent fPSA for Chinese men was > or = 15%.

The percent fPSA may be more useful than PSA in the detection of prostate cancer. With the percent fPSA dropping down, the pathological differentiating grade of PCa appears lower, but the clinical stage is high, the malignant degree is also increased. The reference range of > or = 15% percent fPSA is more appropriate threshold value for diagnosing the prostate cancer in Chinese man population.