Background. Prostate specific antigen (PSA) does not appear to have the specificity to distinguish between benign prostate hyperplasia and cancer when the PSA is low. PSA density is thought by many to improve the specificity for cancer; however, this theory remains controversial.
Methods. The authors retrospectively reviewed 220 carcinomas in radical prostatectomy specimens and examined the relationship of PSA and PSA density to prostate volume, Gleason sum, and pathologic stage.
Results. Prostate specific antigen and PSA density parallel each other and do not appear to correlate statistically with displaced volume of the prostate, Gleason sum, or pathologic stage. However, PSA density in the PSA 4.1-10 ng/ml group may have conferred unique information secondary to increased variation in prostate volume. Furthermore, PSA density was associated more than PSA with carcinoma in the PSA I 4.0 ng/ml group. A PSA density cutoff of greater than 0.05 ng/ml/ml was accurate in the diagnosis of 94.9% of the patients with cancer. Finally, carcinomas with a Gleason sum of greater than 6 in patients with a PSA density of greater than 0.3 ng/ml/ml had a high probability of being extracapsular at the time of surgery.
Conclusions. Although PSA and PSA density appear to mirror each other in many ways, PSA density confers unique information and may be used as an adjunct to PSA and digital rectal examination in the detection and staging of prostate cancer. If prostate needle biopsy is performed, PSA density and Gleason sum may help identify From the