Open AccessUsing the Free‐to‐total Prostate‐specific Antigen Ratio to Detect Prostate Cancer in Men with Nonspecific Elevations of Prostate‐specific Antigen Levels
Author(s) -
Hoffman Richard M.,
Cla David L.,
Littenberg Benjamin,
Frank Joseph J.,
Peirce John C.
Publication year - 2000
Publication title -
journal of general internal medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.746
H-Index - 180
eISSN - 1525-1497
pISSN - 0884-8734
DOI - 10.1046/j.1525-1497.2000.90907.x
Subject(s) - medicine , prostate cancer , prostate specific antigen , interquartile range , receiver operating characteristic , generalizability theory , prostate , urology , likelihood ratios in diagnostic testing , cancer , cut point , prostate cancer screening , biopsy , pre and post test probability , gynecology , oncology , statistics , mathematics
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.