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Predicted prostate specific antigen results using transrectal ultrasound gland volume. Differentiation of benign
F Lee1, P J Littrup, L Loft-Christensen
1Department of Radiology, St. Joseph Mercy Hospital, Ann Arbor, Michigan 48106.
Methods:
The diagnostic performance of transrectal ultrasound (TRUS) gland volume and prostate specific antigen (PSA) results were evaluated in 204 men consecutively scheduled to undergo transurethral prostatic resection (TUR).
Results:
Nonpalpable prostate cancer was detected by TRUS alone in 18% (29 of 161) and by TUR alone in 9% (14/161), for an overall cancer incidence of 27%. A predicted PSA value (TRUS gland volume x 0.20 ng/ml/g = polyclonal PSA) was used for comparison with serum PSA for each patient. TRUS positive predictive value improved from 52% to 86% when serum PSA exceeded the predicted value. The specificity and positive predictive value of PSA at 2.5 ng/ml were 23% and 37%, respectively, which increased to 88% and 72%, respectively, when serum PSA exceeded the predicted value.
Conclusions:
Predicted PSA values produce decision levels near the 95th percentile for each patient and assist individual biopsy decisions better than grouped gland volume ranges. Wider application of TRUS and PSA in any clinical setting or early detection program is now possible.