THE USE OF PERCENT FREE PROSTATE-SPECIFIC ANTIGEN FOR STAGING CLINICALLY LOCALIZED PROSTATE-CANCER

Purpose: The free-to-total serum prostate specific antigen (PSA) ratio (percent free PSA) has been demonstrated to have clinical use for ear ly detection of men with prostate cancer with total PSA levels between 4.0 and 10.0 ng/ml. Several studies evaluating the usefulness of perc ent free PSA for the staging of clinically localized prostate cancer h ave provided conflicting results. We further investigate the usefulnes s of percent free PSA for staging of clinically localized prostate can cer. Materials and methods: In 263 men with clinically localized prost ate cancer who underwent radical prostatectomy total PSA and free PSA were measured preoperatively. Pathological stages were classified as o rgan confined in 134 cases, capsular penetration in 92, seminal vesicl e involvement in 7, involvement of the surgical margins and 20 and lym ph node involvement in 10. Results: Percent free PSA was significantly different between men with organ confined versus nonorgan confined tu mors (p-less-than-0.0001) and between those with favorable versus unfa vorable pathology (p-less-than-0.0001). A cutoff of 12% free PSA provi ded a 72% positive predictive value and 52% negative predictive value for favorable pathology. A cutoff of 15% free PSA provided a 76% and 5 3% positive and negative predictive value, respectively, for organ con fined disease. Conclusions: These data demonstrate that the use of per cent free PSA may be of additional value for the staging of clinically localized prostate cancer. The recommendations for cutoff levels of p ercent free PSA for detection and staging of localized prostate cancer are preliminary and can only be given for this particular assay. A la rge multicenter trial, controlling for age, stage and PSA assays, is r equired to elucidate this issue further.