Using the free-to-total prostate-specific antigen ratio to detect prostate cancer in men with nonspecific elevations of prostate-specific antigen levels
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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.
- Using the free-to-total prostate-specific antigen ratio to detect prostate cancer in men with nonspecific elevations of prostate-specific antigen levels
Journal of General Internal Medicine
Volume 15, Issue 10 , pp 739-748
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- prostatic neoplasm
- prostate-specific antigen
- diagnostic accuracy
- free PSA
- Industry Sectors
- Author Affiliations
- 1. the Medicine Service, Albuquerque Department of Veterans Affairs Medical Center, USA
- 2. University of New Mexico School of Medicine, Albuquerque, NM
- 3. Department of Medicine, The University of Vermont, Burlington, Vt
- 4. the Department of Medical Education and Research, Good Samaritan Regional Medical Center, Phoenix, Ariz
- 5. the Laboratory Sciences of Arizona, Phoenix, Ariz