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PSA excess in the differential diagnosis of prostate carcinoma
Objective:
To evaluate the efficiency of PSA excess in distinguishing prostate cancer (PC) in its early stages from benign prostatic hypertrophy (BPH) and compare it with the efficiency of serum PSA.
Methods:
A cross-sectional study was carried out on 27 patients with PC and 46 with BPH, whose serum PSA and prostatic volume were determined. PSA excess was calculated as the difference between serum PSA and predicted PSA according to the gland volume, calculating the latter as the prostatic volume multiplied by factor 0.3 ng/ml/g.
Results:
PSA excess values were significantly higher in patients with PC, while serum PSA levels were not different between the two populations studied. Receiver operating curves (ROC plots) showed a higher diagnostic utility for PSA excess, with a maximum efficiency of 73% at a cut-off point of -13 ng/ml. The predictive value of a positive result is slightly higher for serum PSA, but PSA excess showed a predictive value of a negative result superior to that of PSA.