ROLE OF PROSTATE-SPECIFIC ANTIGEN DENSITY AFTER APPLYING AGE-SPECIFICPROSTATE-SPECIFIC ANTIGEN REFERENCE RANGES

Objectives. To determine the potential role of prostate-specific antig en (PSA) density (PSAD) in the early detection of prostate carcinoma i f we apply age-specific PSA reference ranges (2.5 ng/mL or less for ag es 40 to 49 years, 3.5 or less for ages 50 to 59, 4.5 or less for ages 60 to 69, and 6.5 or less for ages 70 to 79. Methods. We retrospectiv ely reviewed 3234 cases referred to us by urologists for transrectal u ltrasound (TRUS) between January 1, 1991, and September 28, 1993. We i ncluded 2429 patients in the study, ages 40 to 79 years, with Hybritec h or Abbott IMx serum PSA determinations and without previously diagno sed prostate cancer. We performed digital rectal examination (DRE) and TRUS in all cases, and TRUS-guided biopsies when indicated. We used s tringent criteria to define 736 cases without clinical evidence of mal ignancy that were designated as a ''benign group. Results. In the beni gn group, we found serum PSA to increase with age in parallel with the increase in prostate volume with age (r = 0.25 and r = 0.26, respecti vely). The association between serum PSA and prostate volume was stron ger (r = 0.46). Using multiple regression analysis, prostate volume ac counted for 18% of the variation in serum PSA, whereas age accounted f or only an additional 2%. PSAD, which directly relates serum PSA to pr ostate volume, showed a weak association with age (r = 0.1). In the en tire study population of 2429 cases, 555 patients had negative DRE and TRUS results and a serum PSA level between the age-specific upper lim it of normal and 10.0 ng/mL. According to the proposed age-specific al gorithm, these patients would have required automatic biopsies. Of the se, 315 cases (56.8%) still had a PSAD of less than 0.15. We performed biopsies in 108 of these 315 and detected only two cancers, for a pos itive biopsy rate (PBR) of 1.9%. The remaining 240 cases had a PSAD of 0.15 or higher, and we performed biopsies in 217 of these cases and d etected 59 cancers, for a PBR of 27.2%. Conclusions. The use of age-sp ecific PSA reference ranges does not totally account for the effect of prostate volume on serum PSA. Therefore PSAD can still be used to red uce safely the number of biopsies performed in patients with negative DRE and TRUS results and a serum PSA level 10.0 ng/mL or less and abov e the age-specific upper limit of normal.