Prostate-Specific Antigen ‘Velocity’ as a Diagnostic Test for Prostate Cancer

Abstract

Background

Prostate-specific antigen “velocity” (slope) is promoted as a diagnostic test for prostate cancer, but its clinical usefulness is uncertain. Accordingly, we evaluated the sensitivity of prostate-specific antigen (PSA) velocity among men who are diagnosed subsequently with prostate cancer.

Methods

Among 64,545 men receiving primary care at any of nine Veterans Affairs Medical Centers during 1989-1990, 1,313 men at least 50 years old had an incident diagnosis of prostate cancer during 1991-1995. PSA velocity values obtained prior to diagnosis (“test”) were compared with results from prostate biopsies (“truth”).

Results

Among men (n = 493) with at least two tests before diagnosis, the sensitivity of PSA velocity ≥ 0.75 ng/mL/yr was 75.5% (95% confidence interval [CI] 71.7-79.3) overall and 48.1% (95% CI 34.8-61.5) among men with normal values of PSA (< 4.0 ng/mL). Based on published data for specificity and prevalence, the estimated positive predictive value of PSA velocity ≥ 0.75 ng/mL/yr is as low as 5%.

Conclusion

PSA velocity may have limited usefulness as a diagnostic test for prostate cancer.