Diagnostic value of prostatic acid phosphatase and prostate-specific antigen in patients with prostatic cancer.

To compare the clinical usefulness of the measurement of prostatic acid phosphatase (PAP) and prostate-specific antigen (PSA) in serum of patients with prostatic carcinoma, we studied 128 patients with prostatic pathology, sixty (46.9%) of whom had prostatic cancer. Receiver-operating characteristics (ROC) curves were constructed and the underlying areas were calculated and compared to study clinical efficiency of the two markers regardless of the cutoff level selected. The area for PSA (0.90 +/- 0.30) was significantly higher (p less than 0.001) than that of PAP (0.71 +/- 0.05) showing that PSA was a better discriminator of the patients with or without prostatic cancer. The maximal clinical efficiency of the two tests at selected cutoff levels (0.8 U/L for PAP and 10 micrograms/L for PSA) was 0.787 and 0.883, respectively, confirming the superiority of PSA. However, the associated determination of the two markers improved the clinical specificity with no false-positive cases.