PROSTATE-SPECIFIC ANTIGEN DENSITY IN PATIENTS WITH HISTOLOGICALLY PROVEN PROSTATE CARCINOMA

Background. Prostate specific antigen (PSA) does not appear to have th e specificity to distinguish between benign prostate hyperplasia and c ancer when the PSA is low. PSA density is thought by many to improve t he specificity for cancer; however, this theory remains controversial. Methods. The authors retrospectively reviewed 220 carcinomas in radic al prostatectomy specimens and examined the relationship of PSA and PS A density to prostate volume, Gleason sum, and pathologic stage. Resul ts. 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 th e PSA 4.1-10 ng/ml group may have conferred unique information seconda ry to increased variation in prostate volume. Furthermore, PSA density was associated more than PSA with carcinoma in the PSA less than or e qual to 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 canc er. Finally, carcinomas with a Gleason sum of greater than 6 in patien ts with a PSA density of greater than 0.3 ng/ml/ml had a high probabil ity of being extracapsular at the time of surgery. Conclusions. Althou gh PSA and PSA density appear to mirror each other in many ways, PSA d ensity confers unique information and may be used as an adjunct to PSA and digital rectal examination in the detection and staging of prosta te cancer. If prostate needle biopsy is performed, PSA density and Gle ason sum may help identify patients who are at high risk for surgical failure.