Use of percent free prostate-specific antigen as a predictor of the pathological features of clinically localized prostate cancer.

Abstract

To evaluate the usefulness of percent free serum prostate-specific antigen (PSA) as a predictor of the pathological features of prostate cancer. Total and free serum PSA were measured preoperatively in 220 consecutive patients with clinically localized prostate cancer who underwent radical prostatectomy. Organ-confined disease and favorable pathology were considered as the outcomes for this study. Percent free serum PSA was not able to predict these outcomes in the overall population. However, it could significantly predict favorable pathology in a subset of patients in whom digital rectal examination (DRE) was normal and total PSA ranged from 4.1 to 10 ng/ml. A 11% cutoff provided a significant distribution with an odds ratio of 2.8 (95% confidence interval 1.1-7.0), a positive predictive value of 63. 3% and a negative predictive value of 46.3%. According to these results, we suggest that percent free PSA may provide additional information for the staging of clinically localized prostate cancer. However, the reference population for its usefulness would be those patients with normal DRE and total PSA between 4.1 and 10 ng/ml.