Comparison of Percent Free Prostate Specific Antigen and Prostate Specific Antigen Density as Methods to Enhance Prostate Specific Antigen Specificity in Early Prostate Cancer Detection in Men With Normal Rectal Examination and Prostate Specific Antigen Between 4.1 and 10 ng./ml.

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Abstract
We analyzed the behavior of prostate specific antigen (PSA) density and percent free PSA to enhance the specificity of PSA in the early diagnosis of prostate cancer in men with normal digital rectal examination and PSA serum level between 4.1 and 10 ng./ml. PSA serum level, PSA density and percent free PSA were analyzed in 74 men with normal digital rectal examination and PSA serum level between 4.1 and 10 ng./ml. All men underwent systematic prostate biopsy, and the diagnosis was benign prostate hyperplasia in 52 and prostate cancer in 22. Furthermore, we determined the decrease in unnecessary biopsies and the cancer detection rate using 0.10 versus 0.15 as cut points for PSA density, and 20 versus 25 as cut points for percent free PSA. In patients with benign prostatic hyperplasia and prostate cancer, respectively, the median PSA level was 6.7 and 7.0 ng./ml. (p > 0.05), median prostate volume was 50 and 37 cc (p < 0.04), median PSA density was 0.14 and 0.19 (p < 0.007) and median percent free PSA was 18.9 and 10.1 (p < 0.005). Using PSA density cut points of 0.15 and 0.10, the decrease in negative biopsies was 53.8 and 36.5% with a sensitivity of 86.4 and 90.9%, respectively. However, using percent free PSA cut points of 20 and 25, the decrease in negative biopsies was 36.5 and 26.9% with a sensitivity of 77.3 and 95.5%, respectively. Although both methods could minimize unnecessary biopsies in men with normal digital rectal examination and PSA serum level between 4.1 and 10 ng./ml., the percent free PSA was more cost-effective since transrectal ultrasound was not required. In this small series of symptomatic patients a percent free PSA cut point of 25 could detect at least 95% of prostate cancers and decrease 26.9% of negative biopsies.