THE USE OF PROSTATE-SPECIFIC ANTIGEN DENSITY TO IMPROVE THE SENSITIVITY OF PROSTATE-SPECIFIC ANTIGEN IN DETECTING PROSTATE CARCINOMA

Background. Prostate specific antigen (PSA) is useful as a tumor marker for monitoring patients with prostate cancer after definitive therapy. Limitations have been noted when PSA was used for the early detection of prostate cancer. The use of prostate specific antigen density [PSAD = PSA (ng/ml)/prostate volume (cc)] has been suggested to differentiate benign from malignant prostate disease. Methods. A retrospective analysis of 559 men who underwent transrectal prostate ultrasound and biopsy for an abnormal PSA value (> 4.0 ng/ml) and/or an abnormal prostate gland by digital rectal examination (DRE) was performed. Prostate specific antigen density evaluation was performed on all men, and its utility for diagnosing prostate cancer was compared with those of PSA and DRE. Results. Two hundred, sixty seven 47%) of the 559 men had positive biopsies for prostate cancer. Sixty-one men had PSA levels of less than 4.0 ng/ml, and 17 (27.8%) of these men had positive biopsies for prostate cancer. No patient with a normal DRE had a positive biopsy regardless of the prostate specific antigen density (PSAD) value. PSAD was not more useful than PSA alone in detecting prostate cancer in this group. Two hundred, seventy-seven men had PSA values between 4.1 and 10.0 ng/ml, and 110 (40.0%) had positive biopsies for prostate cancer. For this group as a whole, the mean PSA values of the positive and negative biopsy groups showed no significant difference. The mean PSAD was significantly different (P < 0.0001) between the positive and negative biopsy groups. Two hundred, twenty-one men had PSA values of greater than 10.0 ng/ml, and 140 (63%) had positive biopsies for prostate cancer. Prostate specific antigen density was no more useful than PSA alone in distinguishing men with positive or negative biopsies for prostate cancer in the entire group. In the subset of patients with a normal DRE, (including no benign prostatic hyperplasia) the mean PSAD appeared-useful (P < 0.004) in distinguishing the positive from the negative biopsy groups, whereas the mean PSA was not. Conclusion. These results suggest that PSAD is useful in discriminating prostate cancer in men with normal DRE and PSA levels between 4.1 and 10.0 ng/ml.