Journal of General Internal Medicine

, Volume 15, Issue 10, pp 739–748

Using the free-to-total prostate-specific antigen ratio to detect prostate cancer in men with nonspecific elevations of prostate-specific antigen levels

Authors

    • the Medicine ServiceAlbuquerque Department of Veterans Affairs Medical Center
    • University of New Mexico School of Medicine
  • David L. Clanon
    • the Medicine ServiceAlbuquerque Department of Veterans Affairs Medical Center
  • Benjamin Littenberg
    • Department of MedicineThe University of Vermont
  • Joseph J. Frank
    • the Department of Medical Education and ResearchGood Samaritan Regional Medical Center
    • the Laboratory Sciences of Arizona
  • John C. Peirce
    • the Department of Medical Education and ResearchGood Samaritan Regional Medical Center
Review

DOI: 10.1046/j.1525-1497.2000.90907.x

Cite this article as:
Hoffman, R.M., Clanon, D.L., Littenberg, B. et al. J GEN INTERN MED (2000) 15: 739. doi:10.1046/j.1525-1497.2000.90907.x

Abstract

BACKGROUND: Prostate-specific antigen (PSA) levels between 4.0 to 10.0 ng/ml have poor specificity in prostate cancer screening, leading to unnecessary biopsies.

OBJECTIVE: To determine whether the free-to-total PSA ratio (F/T PSA) improved the diagnostic accuracy of these nonspecific PSA levels.

MEASUREMENTS AND MAIN RESULTS:Medline was searched from 1986 to 1997. Additional studies were identified from article bibliographies and by searching urology journals. Two investigators independently identified English-language studies providing F/T PSA ratio test-operating characteristics data on ≧10 cancer patients with PSA values between 2.0 and 10.0 ng/ml. Twenty-one of 90 retrieved studies met selection criteria. Two investigators independently extracted data on methodology and diagnostic performance. Investigator-selected cut points for the optimal F/T PSA ratio had a median likelihood ratio of 1.76 (interquartile range, 1.40 to 2.11) for a positive test and 0.27 (0.20 to 0.40) for a negative test. Assuming a 25% pretest probability of cancer, the posttest probabilities were 37% following a positive test and 8% following a negative test. The summary receiver operating characteristic curve showed that maintaining test sensitivity above 90% was associated with false positive rates of 60% to 90%. Methodologic problems limited the validity and generalizability of the literature.

CONCLUSIONS: A negative test reduced the posttest probability of cancer to approximately 10%. However, patients may find that this probability is not low enough to avoid undergoing prostate biopsy. The optimal F/T PSA ratio cut point and precise estimates for test specificity still need to be determined.

Key Words

prostatic neoplasmprostate-specific antigendiagnostic accuracyfree PSA

Copyright information

© Society of General Internal Medicine 2000