[Utility of prostate specific antigen (PSA) density in detecting prostate cancer in men showing gray zone serum PSA levels].

The efficacy of prostate specific antigen density (PSAD) in diagnosing prostate cancer was assessed in 98 patients with serum prostate specific antigen (PSA) levels between 2 and 10 ng/ml who had a pathological diagnosis made by prostate biopsy or transurethral resection of the prostate. Of the 98 patients, 22 (22%) had prostate cancer. The PSA (based on a cut-off value of 4.5 ng/ml) had a sensitivity and positive predictive value (PPV) of 82% and 38%, respectively, for diagnosing prostate cancer, while the results for PSAD (based on a cut-off value of 0.13) were 91% and 61%. The PSAD was more efficient than the PSA levels and was also superior to digital rectal examination (DRE) combined with transrectal ultrasonography (TRUS), for which the sensitivity and PPV were 73% and 39%, respectively. Six (11%) out of 57 patients who were normal on DRE and TRUS had prostate cancer. In these 57 patients, the PSA (cut-off value: 4.5 ng/ml) had a sensitivity of 50% and PPV while the values for PSAD (cut-off value: 0.13) were 83% and 36% respectively. The PSAD could effectively detect even impalpable prostate cancer not visible on TRUS.